It's been a turbulent week on Wall Street, and Friday is shaping up to bring the week to a fitting conclusion. Because of how the futures and options markets work, the third Friday of the last month of each quarter often brings considerable volatility. The resulting nervousness was apparent at the market's open, as the S&P 500 (^GSPC 0.02%) was down about a quarter-percent.

A pair of stocks gave good examples of how much share prices can move depending on the news that a company gives. FedEx (FDX 0.18%) moved sharply higher following the release of its latest financial results, as shareholders generally liked what they saw. However, Sarepta Therapeutics (SRPT -8.21%) headed in the other direction, having disappointed investors with its most recent news.

FedEx boosts its outlook

Shares of FedEx rose 11% near the open Friday. The delivery specialist's stock responded to fiscal third-quarter financial results for the period ending Feb. 28 that showed considerable resilience in FedEx's core business and optimism for what the future will bring.

To be clear, FedEx wasn't able to avoid the impact of the economic slowdown. Quarterly revenue came in at $22.2 billion, down from $23.6 billion in the year-ago period. Adjusted net income came in at $865 million, and adjusted earnings of $3.41 per share were down 26% year over year. FedEx cited weak demand across the market, particularly for its Express division. Global inflation also hurt FedEx's bottom line by raising some of its operating costs.

However, FedEx was able in part to use its pricing power to stay strong. The ground and freight segments both saw revenue per shipment rise 11% from year-ago levels, and moves to reduce costs were able to offset some of the weaker shipment volume that weighed on overall results.

Investors also liked that FedEx raised its full-year guidance, as the shipping giant now sees adjusted earnings of $14.60 to $15.20 per share. That's up from the previous range of $13 to $14 per share, and the company believes that its initiatives to bolster profit are building positive momentum that will enable FedEx to weather whatever macroeconomic storms lie in its path.

The FDA surprises Sarepta

Unfortunately, shareholders in Sarepta Therapeutics weren't as fortunate. Sarepta stock fell 20% at the open as investors got their first chance to respond to surprising news from the U.S. Food and Drug Administration (FDA).

The move lower came as Sarepta announced that the FDA would hold an advisory committee meeting for its candidate treatment SRP-9001 for Duchenne muscular dystrophy. That was a shock to shareholders because Sarepta had said less than three weeks ago that it believed the FDA wouldn't need to hold that meeting.

Even so, CEO Doug Ingram was as upbeat as possible about the prospects for Sarepta to come through with an approval. Although Ingram expressed disappointment at having given conflicting information, he was confident that Sarepta's preparations for an advisory committee meeting will give the company a chance to present strong evidence supporting the potential benefits of its candidate treatment in advance of the scheduled action date in late May.

The move lower in Sarepta stock wiped out the gains following the company's last earnings report and the previous announcement about SRP-9001. Now, it appears there could be considerable uncertainty until the biotech company and the FDA go through their regulatory process.