The efficient market theory would be violated if investors earned extraordinary returns months after a company announced unexpected profits. Thus, the correct option is (d.) Investors earn abnormal returns months after a firm announces surprise earnings.
The efficient-market hypothesis is a financial economics concept that asserts asset prices represent all available information. Because market prices should only react to fresh information, it is impossible to continually "beat the market" on a risk-adjusted basis.
Because the EMH is expressed in terms of risk adjustment, it can only offer testable predictions when combined with a specific risk model. As a result, financial economics research has focused on market anomalies, or departures from specified risk models, since at least the 1990s.
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