Berkshire Hathaway's Class A stock slipped below $100,000 for the first time since January 2010 amid broader market declines and concern about the health of the economy.The Class A shares of billionaire investor Warren Buffett's company traded as low as $98,952 Thursday, but rebounded to close at $100,000. The more affordable Class B shares traded as low as $65.35, during the day. The Standard & Poor's 500 index dropped 3.2 percent. Over the past year, Berkshire's Class A shares declined nearly 19 percent from $124,865 to Wednesday's closing price of $101,250. By contrast, the S&P 500 index that Buffett measures his company's progress against was up about 2 percent from a year earlier at Wednesday's close. ___ Nike's 1Q net income rises 15 percent Nike Inc.'s fiscal first-quarter net income rose 15 percent as sales of its athletic gear rose faster than its costs. The world's largest athletic shoe and clothing maker reported after the market closed Thursday that it earned $645 million, or $1.36 per share, for the quarter that ended Aug. 31. That's up from $559 million, or $1.17 per share, in the same quarter last year. Nike's revenue rose 18 percent to $6.08 billion. Excluding the impact of foreign exchange rates, revenue rose 11 percent. Nike, based in Beaverton, Ore., said demand for its product remained strong around most of the globe. That helped make up for the higher prices it paid for raw materials and for selling more things at a discount, both of which hurt its profit margins during the period. ___ Fewer people applied for unemployment benefits The number of people applying for unemployment benefits fell last week, though the decline isn't enough to signal improvement in the job market. Weekly applications dropped by 9,000 to a seasonally adjusted 423,000, the Labor Department said Thursday. The four-week average, a less volatile figure, rose slightly for the fifth straight week to 421,000.