The S&P 500 Index (^GSPC -0.16%) edged higher on Thursday, finishing at another all-time high, its fourth such record in the past six trading days. Fueling the bullishness were jobless claims, which came in lower than expected, giving Wall Street hope that tomorrow's monthly payrolls report will show at least modest improvement in the labor market. The S&P 500 added three points, or 0.2%, to end at 1,877. 

Not helping the labor market (or its own shareholders), office supply retailer Staples (SPLS) cratered 15.3% in trading today, ending as the worst performer in the 500-stock index by a long shot. Staples investors tuning in to the earnings call may have mistaken it for a nightmare, as the company posted underwhelming fourth-quarter results, forecast a lousy first quarter of more sales slumps, and decided to close 12% of its North American retail locations. Awful quarter aside, I applaud Staples for shifting its focus to online sales, where the company has had success as a business-facing office supplies provider.

New Jersey-based pharmaceutical company Actavis (AGN) saw its stock shed 4.7% today, finishing as the second-worst performer in the index. Health care was the most unpopular sector in the stock market Thursday, so Actavis was swimming against the tide. But today's dip is nothing other than a meaningless road bump when taking the long-term perspective. Actavis is fresh off making a blockbuster $25 billion deal -- one of the five largest in its industry in the past decade -- to acquire Forest Laboratories, a move that sent both stocks soaring on the news last month. The addition of Forest Labs gives Actavis, a generic drug maker, a larger hand in the specialty pharmaceutical game, which should boost margins and serve to diversify. 

Seagate Technology (STX), another stock that's been hot during the last year, lost some of its steam today, and fell 4.7% in the process. There wasn't much major news behind today's move, and the data storage company certainly finds itself in an industry with constantly growing demand. With the growth of cloud computing and "big data," Seagate's services are more relevant and timely than ever. With cloud-based services not going anywhere anytime soon, more and more businesses are seeing the need to offer them to retain and recruit customers. Enter Seagate, which produces drives for enterprise servers, offers data storage for businesses, and even external drives for individuals. Also offering a 3.3% dividend, Seagate is an exciting stock that just got a little cheaper after today's 4.7% sale.