Friday was another solid day for the stock market, and the Nasdaq Composite led most major benchmark indexes higher. Strong performance by the technology sector was a key driving force behind the market's overall gains, but other factors lent momentum to the upward move, including a jump of more than $1 per barrel in crude oil prices, which finished the week just under $56 per barrel.

Some companies, though, couldn't share in the broader positive sentiment. After delivering quarterly reports that dissatisfied investors, (NASDAQ:STMP), Pacific Biosciences of California (NASDAQ:PACB), and Frontier Communications (OTC:FTR) were among the worst performers on Friday. Below, we'll look more closely at the results and news that drove their share prices down. gets returned to sender plunged more than 20% despite what appeared to be an upbeat set of results for its third quarter. Revenue rose by 24% year over year, and net income more than doubled. The online postage service also boosted its guidance for the year, pointing to even more encouraging news about its future. Yet investors weren't satisfied with the results. The stock price had doubled since late April, and at those valuations, the market viewed anything short of perfection as justifying a sell-off. Little appears to be wrong with's fundamental performance, though, so the key question is whether its valuation really had gotten ahead of itself, or whether Friday's drop will in the longer-term prove unjustified.

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Pacific Biosciences gets out of order

Pacific Biosciences of California finished the day down more than 25% after releasing its third-quarter financial report. The company that made revolutionary progress in the DNA-sequencing field saw revenue shrink from year-ago levels, and losses for PacBio were wider than in 2016's Q3. The company has been banking on raising more revenue from sales of its Sequel sequencing equipment, but it has also had to deal with upgrading older customers from outdated equipment to the newest versions available. Moreover, after losing a key contract with industry giant Roche, Pacific Biosciences will have to work hard to regain ground in the months ahead.

Frontier drops the call

Finally, Frontier Communications fell 19%. After the telecom company reported disastrous third-quarter results earlier this week that included an 11% drop in revenue and another net loss, the other shoe dropped late Thursday night, when bond rating agency Moody's downgraded its rating on Frontier from B2 to B3. The agency cited Frontier's declining subscriber base, as well as its substantial refinancing risk beginning in 2020 and beyond. Moody's also pointed to Frontier's dividend as a negative credit factor, leading some to believe that the payout could be in danger. With the stock down more than 85% just since the beginning of the year, Frontier may be running out of time to figure out a viable path forward.

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