Wall Street was able to claw back some of its lost ground on Friday, as the Dow Jones Industrial Average bounced back from about 1,250 points' worth of losses on Wednesday and Thursday. Major benchmarks were up anywhere from 1% to 2%, but some investors weren't pleased to see that the small-cap Russell 2000 Index wasn't able to join its larger-cap peers in posting similar gains. Largely forgotten amid the market's volatility is the fact that third-quarter earnings season is underway, and some stocks suffered from disappointing results. PNC Financial Services Group (NYSE:PNC), Wabash National (NYSE:WNC), and Momenta Pharmaceuticals (NASDAQ:MNTA) were among the worst performers on the day. Here's why they did so poorly.

PNC anticipates slow growth ahead

Shares of PNC Financial Services Group fell almost 6% after the company announced its third-quarter financial results. The banking institution said that net income rose 3% from the second quarter, while total revenue was higher by 1%. Higher loan yields helped to lift net interest income by 2%, but noninterest income dropped by 1% to partly offset those gains. Although credit quality remained strong, average loans were up only marginally from three months ago, and PNC anticipates the slow pace of loan growth to continue for the remainder of the year. PNC has held up well overall, but today's report shows some of the challenges that even healthy financial institutions face in the current industry environment.

Big bank vault with open door and partial view inside.

Image source: Getty Images.

This big-rig trailer maker has a big problem

Wabash National stock dropped 19% in the wake of the company's preliminary release of third-quarter results. The manufacturer of semitrailers and liquid transportation systems said that it expects revenue to come in between $550 million and $555 million this quarter, up from $425 million a year ago, but net income will be just $0.06 to $0.09 per share. That bottom-line figure is down 70% to 80% from the third quarter of 2017, and Wabash explained that even after making allowances for some one-time items, adjusted earnings would still likely be off between 10% and 20%. CEO Brent Yeagy characterized the period as "a challenging and difficult quarter" due to higher costs and flagging demand from purchasers. Wabash has been optimistic about the future all year, but shareholders seem to be in a show-me state of mind before they'll be willing to have confidence in the company's future.

Momenta loses momentum

Finally, shares of Momenta Pharmaceuticals finished down 13.5%. The drug company continued to lose ground following a disappointing performance on Thursday, when the stock also dropped a double-digit percentage after Momenta made announcements about its drug pipeline plans. The company has gone through a difficult transition, having had to watch revenue decline while expenses soar, and investors were hoping that the company's research and development day presentation would show a clearer direction forward for Momenta. Instead, shareholders will have to wait a while before key candidate drugs make it through clinical trials, without any assurance that their patience will ultimately be rewarded.

Dan Caplinger has no position in any of the stocks mentioned. The Motley Fool recommends Momenta Pharmaceuticals. The Motley Fool has a disclosure policy.