Systematic vs. Unsystematic Risk - Corporate Finance

1. A researcher is conducting an event study to measure the stock market's reaction to merger announcements. The researcher calculates abnormal returns by taking the actual stock return on the announcement day and subtracting the expected return predicted by the CAPM (based on the market's return that day and the stock's beta). This abnormal return is a proxy for the financial impact of:
   Answer: the materialization of unsystematic, firm-specific risk. Event studies are designed to isolate the market's reaction to specific company news by separating expected returns from unexpected price movements. When you calculate abnormal returns using CAPM, you're measuring how much the stock moved beyond what the market model predicted based on systematic risk factors. The correct answer is D because abnormal returns capture the impact of firm-specific, unexpected information. When a merger is announced, this represents new, company-specific news that wasn't previously reflected in the stock price. Since CAMP already accounts for systematic risk through beta and market returns, any remaining abnormal return must be due to unsystematic (firm-specific) risk materializing as new information hits the market. Here's why the other options are incorrect: Option A is wrong because CAPM already controls for systematic risk through the stock's beta and market return - the abnormal return is what's left after removing systematic risk effects. Option B misses the point because abnormal returns specifically isolate the unexpected component, not total risk, which would include both systematic and unsystematic elements that were already anticipated. Option C incorrectly suggests the abnormal return measures a change in beta itself, when actually CAPM uses the stock's existing beta as a given parameter to predict expected returns. Remember this key distinction for event studies: normal returns reflect systematic risk factors the market already knew about, while abnormal returns capture the surprise impact of new, firm-specific information. This is what makes event studies powerful tools for measuring how quickly markets incorporate company-specific news.
2. Which of the following events would be the clearest example of a source of systematic risk for an automobile manufacturer?
   Answer: A central bank's decision to significantly increase interest rates. Systematic risk affects the entire economy or a large number of assets. A central bank's interest rate hike affects borrowing costs for consumers and corporations across all sectors, influences exchange rates, and alters discount rates for all investments, making it a clear source of systematic risk. The other options—a plant fire, a product recall, and a company-specific labor strike—are all examples of unsystematic risk, as their primary impact is confined to the specific company.
3. An institutional investor is comparing two investment strategies: Strategy X involves buying individual stocks after thorough fundamental analysis, while Strategy Y involves buying broad market index funds. If the investor's primary goal is to minimize unsystematic risk while maintaining market exposure, which approach is most appropriate and why?
   Answer: Strategy Y, because broad market index funds automatically diversify away unsystematic risk while maintaining full exposure to systematic market risk When you encounter questions about risk management and portfolio construction, focus on the fundamental distinction between systematic risk (market-wide risk that affects all securities) and unsystematic risk (company-specific risk that can be diversified away). Strategy Y (broad market index funds) is the most appropriate approach because diversification is the key to eliminating unsystematic risk. Index funds hold hundreds or thousands of stocks across different sectors, which statistically drives company-specific risks toward zero while maintaining full exposure to market movements. This achieves exactly what the investor wants: minimal unsystematic risk with preserved market exposure. Looking at why the other answers miss the mark: Answer B incorrectly assumes that fundamental analysis can consistently identify superior risk-adjusted returns, but research shows that even skilled analysts struggle to beat diversified market returns after accounting for costs and risk. Answer C makes a critical error by claiming concentrated positions reduce risk—in reality, concentration increases unsystematic risk since you're more exposed to individual company problems. Answer D is fundamentally wrong because index funds cannot eliminate systematic risk; they're designed to capture market returns, which inherently includes systematic risk. The key insight is that diversification works through the mathematical principle that uncorrelated risks cancel each other out, but only unsystematic risks are truly uncorrelated. Systematic risks affect all securities simultaneously. Study tip: Remember that diversification is a "free lunch" in finance—it reduces risk without reducing expected returns, but it only works on unsystematic risk. Questions testing this concept often present active management as a tempting alternative to test your understanding of diversification benefits.
4. An investor's portfolio consists of 15 stocks from different industries. The portfolio's beta is 1.1. The investor decides to add a 16th stock, which has a beta of 0.7 and is in an industry not yet represented in the portfolio. What is the most likely combined effect on the portfolio's risk?
   Answer: Both systematic and unsystematic risk will decrease. Adding a stock with a beta (0.7) that is lower than the portfolio's current beta (1.1) will lower the weighted-average beta of the new portfolio. This represents a decrease in systematic risk. Adding another stock to a 15-stock portfolio, especially from a new industry, will also increase its diversification, which reduces the portfolio's remaining unsystematic risk. Therefore, both risk components are likely to decrease.
5. Two portfolios have identical expected returns of 12% and identical total risk (standard deviation) of 20%. Portfolio A holds 10 stocks from the same industry, while Portfolio B holds 100 stocks across multiple industries. During a market crisis, both portfolios decline, but Portfolio A experiences a 25% loss while Portfolio B experiences a 15% loss. What does this outcome suggest about the risk composition of these portfolios?
   Answer: Portfolio A had higher unsystematic risk that became apparent during the crisis, while Portfolio B's superior diversification reduced unsystematic risk exposure Despite identical total risk measures, Portfolio A's concentration in one industry exposed it to higher unsystematic risk that manifested during the crisis. Portfolio B's diversification across industries reduced unsystematic risk, leaving primarily systematic risk exposure. During a crisis, unsystematic risks can compound systematic risks for poorly diversified portfolios. Choice A incorrectly attributes the difference to systematic risk when the portfolios should have similar systematic risk exposures. Choice C ignores the clear diversification differences. Choice D incorrectly questions the risk measurements rather than recognizing the composition difference.
6. A pharmaceutical company's stock has a beta of 0.9. During a period when the market rose 8%, the stock rose 12%. The company announced positive results from a Phase III clinical trial during this period. If an investor wants to estimate what portion of the stock's return was due to systematic versus unsystematic factors, which calculation is most appropriate?
   Answer: Systematic return: 7.2%, Unsystematic return: 4.8%, since beta-adjusted market return plus company-specific news explains the total return Systematic return = Beta × Market return = 0.9 × 8% = 7.2%. The unsystematic return is the portion not explained by market movements: 12% - 7.2% = 4.8%. This represents the impact of company-specific news (clinical trial results). Choice B incorrectly uses the full market return instead of the beta-adjusted market return for systematic risk. Choice C incorrectly assumes all return is systematic and that beta incorporates future news. Choice D contains a calculation error and misunderstands that beta measures sensitivity, not excess systematic exposure.
7. An investor adds a new stock to a pre-existing, well-diversified 50-stock portfolio. The new stock has a very high standard deviation of returns but a beta of 1.0. Which of the following is the most likely impact on the investor's portfolio?
   Answer: The portfolio's beta will remain unchanged, and its total risk will only increase negligibly. Since the existing portfolio is already well-diversified (50 stocks), its unsystematic risk is already minimal. Adding a 51st stock will have a negligible effect on further reducing it. The new stock's high standard deviation is mostly due to its high unsystematic risk, but in a well-diversified portfolio, this unsystematic risk is effectively diversified away. The stock's contribution to the portfolio's risk is determined by its systematic risk (beta). Since the new stock's beta (1.0) is likely close to the beta of a broadly diversified portfolio, the portfolio's overall beta will remain largely unchanged. Thus, neither the systematic nor the remaining unsystematic risk of the portfolio will change much, leading to a negligible change in total risk.
8. From the perspective of a domestic U.S. investor holding only U.S. stocks, a sudden political crisis in a small, foreign country is typically considered unsystematic risk. From the perspective of an investor in that small foreign country, the same political crisis is best described as:
   Answer: systematic risk, because it affects nearly all companies and investments within that country. Systematic risk is risk that cannot be diversified away within a given market. For an investor whose entire portfolio is confined to a single country, a major political or economic crisis in that country affects all assets and cannot be avoided by diversifying across domestic industries. Therefore, it acts as systematic risk for that local investor. For a global investor, however, this country-specific risk can be diversified away by investing in other countries, making it appear as unsystematic risk from their broader perspective.
9. When determining the appropriate risk-adjusted discount rate for this project using the CAPM framework, which risk component is the most critical consideration?
   Answer: The high correlation of the project's cash flows with the business cycle. The CAPM framework specifies that the appropriate discount rate depends on the project's systematic risk. Systematic risk is the risk that is correlated with the overall market or economy. The statement that the project's cash flows are highly correlated with GDP growth and the business cycle directly indicates that the project has a high degree of systematic risk. This high systematic risk will translate into a high asset beta, which in turn leads to a higher required rate of return (discount rate). The other options—operational failure and technological obsolescence—are examples of unsystematic risk, which can be diversified away within the corporation and are not priced by the CAPM.
10. A manufacturing company's stock has a total risk, measured by standard deviation, of 40%. The standard deviation of the market portfolio is 20%, and the stock's beta is 1.5. What is the approximate standard deviation of the stock's firm-specific (unsystematic) returns?
    Answer: 26.5% Total variance of a stock is the sum of its systematic variance and unsystematic variance: $\sigma_{Total}^2 = \beta^2 \sigma_M^2 + \sigma_{Unsystematic}^2$. We are given $\sigma_{Total} = 0.40$, $\sigma_M = 0.20$, and $\beta = 1.5$. First, calculate the systematic variance: $\beta^2 \sigma_M^2 = (1.5)^2 \times (0.20)^2 = 2.25 \times 0.04 = 0.09$. Next, use the total variance ($0.40^2 = 0.16$) to find the unsystematic variance: $0.16 = 0.09 + \sigma_{Unsystematic}^2$. This gives $\sigma_{Unsystematic}^2 = 0.16 - 0.09 = 0.07$. Finally, take the square root to find the unsystematic standard deviation: $\sigma_{Unsystematic} = \sqrt{0.07} \approx 0.2645$, or 26.5%.
11. A regression of a stock's monthly returns against the market's monthly returns over five years produces an R-squared value of 0.30. Which of the following is the most accurate interpretation of this result?
    Answer: 70% of the stock's total risk is diversifiable. In a regression of asset returns on market returns, R-squared measures the proportion of the asset's total variance (total risk) that is explained by the market's variance (systematic risk). If R-squared is 0.30, it means 30% of the stock's total risk is systematic. The remaining portion, 1 - R-squared = 1 - 0.30 = 0.70, or 70%, represents the proportion of total risk that is unsystematic, or diversifiable.
12. A biotech startup's stock has exhibited the following pattern: it moves independently of general market trends but shows extreme volatility around FDA approval announcements, clinical trial results, and patent decisions. The stock's correlation with the market index is 0.15. Which statement best characterizes this stock's risk profile?
    Answer: The stock exhibits primarily unsystematic risk, with low systematic risk as evidenced by weak correlation with market movements When you encounter questions about stock risk profiles, focus on distinguishing between systematic risk (market-wide, undiversifiable) and unsystematic risk (company-specific, diversifiable). The key indicator is correlation with market movements. This biotech stock shows a correlation of only 0.15 with the market index, indicating very weak relationship to overall market movements. The extreme volatility occurs around company-specific events like FDA approvals, clinical trials, and patent decisions—these are idiosyncratic factors that don't affect the broader market. This pattern points to predominantly unsystematic risk that could be diversified away in a well-balanced portfolio. Answer C correctly identifies this as primarily unsystematic risk with low systematic risk, supported by the weak market correlation. Answer A incorrectly categorizes regulatory announcements as systematic risk. While FDA decisions affect the pharmaceutical sector, they don't move the entire market—they're industry or company-specific events that represent unsystematic risk. Answer B misinterprets the low correlation as indicating "balanced" risk exposure. Low correlation actually suggests minimal systematic risk exposure, not equal amounts of both risk types. Answer D contains a fundamental misconception about diversification. The fact that biotech regulatory risks affect multiple biotech companies doesn't make them systematic—they can still be diversified away by including non-biotech stocks in a portfolio. True systematic risk affects virtually all securities. Remember: correlation with the market index is your best clue for systematic risk. Low correlation (like 0.15) typically signals predominant unsystematic risk, regardless of how volatile the individual stock appears.
13. An investor holds a market-cap-weighted index fund that tracks the entire stock market. A second investor holds a portfolio of 30 stocks concentrated in a single, non-cyclical industry. By coincidence, both portfolios exhibit the exact same total risk (standard deviation) over the last five years. Which of the following statements must be true?
    Answer: The 30-stock portfolio has a lower beta than the index fund. When you encounter questions comparing portfolios with equal total risk but different diversification levels, focus on the relationship between systematic risk (beta) and unsystematic risk components. Both portfolios have identical total risk, but they achieve this through very different risk compositions. The market-cap-weighted index fund is highly diversified across all sectors, so virtually all its risk comes from systematic (market) risk. The 30-stock concentrated portfolio, while somewhat diversified within its industry, carries significant unsystematic risk due to industry concentration. Since total risk equals systematic risk plus unsystematic risk, and both portfolios have the same total risk, the concentrated portfolio must have lower systematic risk (beta) to compensate for its higher unsystematic risk. This makes answer D correct. Answer A is wrong because higher concentration means the portfolio needs lower, not higher, systematic risk to achieve the same total risk as the diversified index. Answer B incorrectly assumes the 30-stock portfolio has eliminated unsystematic risk—while 30 stocks provide some diversification, concentration in one industry leaves substantial unsystematic risk. Answer C fails because equal total risk doesn't mean equal systematic risk when unsystematic risk levels differ significantly between portfolios. Remember this key principle: when comparing portfolios with equal total risk, the less diversified portfolio will typically have lower beta because it carries more unsystematic risk. Total risk is the sum of both components, so one must be lower when the other is higher.
14. A quantitative analyst calculates that Stock A has generated excess returns with a tracking error of 15% relative to its benchmark, while Stock B has generated similar excess returns with a tracking error of 5% relative to the same benchmark. Both stocks have identical betas of 1.0. What can be inferred about the risk characteristics of these two stocks?
    Answer: Stock A has higher unsystematic risk than Stock B, as evidenced by the greater deviation from benchmark performance When you encounter questions about tracking error and beta, you're dealing with the fundamental distinction between systematic and unsystematic risk. Beta measures systematic risk (market-related risk that affects all securities), while tracking error captures total deviation from a benchmark, including both systematic and unsystematic components. Since both stocks have identical betas of 1.0, they have the same systematic risk exposure to market movements. However, Stock A's tracking error of 15% versus Stock B's 5% reveals a significant difference in their total risk profiles. Tracking error measures how much a security's returns deviate from its benchmark, encompassing both systematic and unsystematic risk factors. With systematic risk held constant (same beta), the higher tracking error must stem from greater unsystematic risk—company-specific factors like management decisions, industry events, or operational issues that cause Stock A to diverge more dramatically from benchmark performance. Answer choice A incorrectly suggests Stock A has higher systematic risk, but identical betas indicate identical systematic risk. Choice B makes the same error in reverse, misattributing the tracking error difference to systematic risk management rather than unsystematic factors. Choice C dismisses the tracking error difference as measurement noise, ignoring the meaningful information about unsystematic risk that tracking error provides when systematic risk is controlled. Remember this pattern: when securities have identical betas but different tracking errors, the difference reflects unsystematic risk. Beta isolates systematic risk, so any additional deviation captured by tracking error must be company-specific, diversifiable risk.
15. From the perspective of a well-diversified investor, how does this event and the subsequent price change primarily relate to the company's risk profile?
    Answer: It represents a realization of unsystematic risk and does not, in itself, imply a change in the stock's beta. The drug breakthrough is a firm-specific event. Its impact on the stock price, independent of the market's movement, is a manifestation of unsystematic (or diversifiable) risk. A diversified investor is exposed to such events for each stock they hold. This single event does not necessarily change the stock's fundamental sensitivity to market-wide economic factors, which is what beta measures. While the resolution of uncertainty is positive, the potential for such large, firm-specific swings is the definition of unsystematic risk.
16. An analyst compares two equity portfolios. Portfolio A is a well-diversified portfolio of 100 stocks from various economic sectors, with a beta of 1.0. Portfolio B consists of 10 stocks, all from the biotechnology industry, and also has a beta of 1.0. Which of the following statements most accurately compares the risk of these two portfolios?
    Answer: Portfolio B has a higher total risk than Portfolio A due to a higher level of unsystematic risk. Total risk is the sum of systematic risk and unsystematic risk. Both portfolios have the same systematic risk because their betas are equal to 1.0. However, Portfolio B is concentrated in a single industry (biotechnology) and is therefore poorly diversified compared to Portfolio A. This concentration means Portfolio B retains a significant amount of firm-specific and industry-specific (i.e., unsystematic) risk. Portfolio A, being well-diversified, has eliminated most of its unsystematic risk. Therefore, Portfolio B will have a higher total risk (as measured by standard deviation) than Portfolio A.
17. Stock X has a beta of 1.3. Stock Y has a beta of 0.9. An analyst observes that the correlation of Stock X's returns with the market is lower than the correlation of Stock Y's returns with the market. Which of the following statements provides the best explanation for this observation?
    Answer: Stock X must have a significantly higher standard deviation of returns than Stock Y. The formula for beta is $\beta_i = \rho_{i,m} \frac{\sigma_i}{\sigma_m}$, where $\rho_{i,m}$ is the correlation of the stock with the market, $\sigma_i$ is the stock's standard deviation, and $\sigma_m$ is the market's standard deviation. If Stock X has a lower correlation ($\rho_{X,m}$) than Stock Y ($\rho_{Y,m}$) but a higher beta, it must be compensated for by a much larger ratio of $\sigma_X / \sigma_m$. This means Stock X's individual volatility (standard deviation) must be significantly higher than Stock Y's.
18. The primary theoretical justification for why the Capital Asset Pricing Model (CAPM) only includes a premium for systematic risk, and not for total risk, is that:
    Answer: investors are assumed to be rational and can eliminate unsystematic risk at virtually no cost through diversification. When you encounter CAPM questions, focus on the model's core assumption about investor behavior and portfolio construction. The CAPM builds on modern portfolio theory, which assumes investors can construct diversified portfolios. The correct answer is D because CAPM's theoretical foundation rests on the assumption that rational investors will diversify their portfolios to eliminate unsystematic risk at minimal cost. Since unsystematic (firm-specific) risk can be diversified away by holding many different stocks, investors shouldn't expect compensation for bearing this type of risk. Only systematic risk—risk that affects the entire market and cannot be diversified away—deserves a risk premium. This is why CAPM's risk premium depends solely on beta, which measures systematic risk. Answer A is wrong because measurement accuracy isn't the theoretical justification for excluding unsystematic risk from CAPM. Both types of risk can be measured, but only one is compensated. Answer B incorrectly suggests the model is based on empirical evidence rather than theoretical assumptions about rational investor behavior. In fact, empirical tests of CAPM have shown mixed results. Answer C misunderstands what "unsystematic risk averaging to zero" means—while unsystematic risks of individual companies may cancel out in a large portfolio, this doesn't explain why investors aren't compensated for bearing such risk in individual securities. Remember this key insight: CAPM pricing models always start with assumptions about investor behavior (rationality, diversification) and then derive what risks should be priced. The theory comes first, then empirical testing follows.
19. An investor holds a portfolio of 500 stocks across all sectors with equal weights. During a recession, the portfolio loses 18% of its value. Simultaneously, a mutual fund that tracks the S&P 500 loses 20% of its value. What can be concluded about the composition of losses in the investor's portfolio?
    Answer: The portfolio experienced approximately 20% systematic risk, with unsystematic risks effectively diversified away, and outperformed due to broader diversification than the S&P 500 With 500 equally weighted stocks across all sectors, unsystematic risk is effectively diversified away. The portfolio's 18% loss represents primarily systematic risk exposure, but the difference from the S&P 500's 20% loss likely reflects different systematic risk exposures (different beta, sector weightings, or market cap exposure) rather than unsystematic risk. Choice A incorrectly treats the performance difference as unsystematic risk. Choice C incorrectly assumes the portfolio loss represents pure systematic risk without considering that different systematic exposures exist. Choice D incorrectly attributes the outperformance to unsystematic risk when it's more likely due to different systematic risk characteristics.
20. From a risk management perspective, which combination of strategies would most effectively address the different types of risks that affected GlobalCorp's stock performance?
    Answer: Use hedging strategies for interest rate risk, while relying on portfolio diversification to address cyber attack and CEO resignation risks When analyzing risk management strategies, you need to match each risk type with the most effective mitigation approach. The three events affecting GlobalCorp represent fundamentally different risk categories requiring distinct strategies. The Federal Reserve interest rate change represents systematic risk that affects all stocks - this is best addressed through hedging strategies like interest rate swaps or futures contracts that directly offset rate exposure. The cyber attack and CEO resignation are company-specific (unsystematic) risks that can be reduced through portfolio diversification, as holding multiple stocks means these isolated events won't devastate your entire portfolio. Answer D correctly pairs hedging for interest rate risk with diversification for the company-specific risks, matching each risk type with its most effective mitigation strategy. Answer A is incorrect because diversification cannot effectively address systematic risks like interest rate changes that affect the entire market simultaneously. Answer B confuses the investor's perspective with corporate management - while corporate policies and insurance are good for the company itself, an investor managing portfolio risk needs different tools. Answer C makes the same error as B, focusing on corporate-level solutions rather than investor-level risk management strategies. The key insight is that systematic risks (affecting all securities) require hedging or other direct offsets, while unsystematic risks (company-specific) are best handled through diversification. Remember this fundamental distinction: diversification reduces unsystematic risk but cannot eliminate systematic risk, which requires targeted hedging strategies.

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