US STOCKS-Wall St falls for 5th day on global economy, earnings concern

* Bank of America (Swiss: BAC.SW - news) , Citi down after results

* Swiss National Bank moves to scrap 3-year euro cap on the franc

* Best Buy shares fall

* Indexes off: Dow 0.6 pct, S&P 0.7 pct, Nasdaq 1.1 pct (Updates to midday, changes byline)

By Caroline Valetkevitch

NEW YORK, Jan 15 (Reuters) - U.S. stocks fell in midday trading Thursday, putting them on track for a fifth day of losses as bank results disappointed and investors focused on concerns about the effect of global weakness on U.S. earnings.

The S&P financial sector, down 1.4 percent, led the day's decline. Bank of America lost 4.3 percent and was among the S&P 500's biggest drags after the second-largest U.S. bank by assets reported a 14 percent slump in quarterly profit. Citigroup (NYSE: C - news) shares fell 3.5 percent after its quarterly results.

Trading was likely to remain volatile through the session after the Swiss National Bank scrapped its cap on the franc.

Swiss stocks traded in the United States moved higher, Credit Suisse (NYSE: CS - news) , up 0.7 percent at $22.98 and Novartis , up 1.9 percent to $98.61, as a strengthening Swiss franc made U.S.-dollar denominated stocks cheaper.

Expectations for U.S. fourth-quarter earnings have fallen sharply in recent months, with growth now estimated at just 3.5 percent, compared with an Oct. 1 estimate of 11.2 percent growth, according to Thomson Reuters data.

"There's a lot of cash still on the sidelines because of the worries over the global economy, over what's going to happen with lower commodity prices," said Eric Marshall, director of research at Hodges Capital Management in Dallas.

Investors are waiting not just results but forecasts from companies, he said. "There's nervousness ... but we think the fourth quarter earnings season will be somewhat of a relief."

Oil prices were down more than 2 percent.

At 12:39 p.m., the Dow Jones industrial average fell 97.95 points, or 0.56 percent, to 17,329.14, the S&P 500 lost 14.15 points, or 0.7 percent, to 1,997.12 and the Nasdaq Composite dropped 50.33 points, or 1.08 percent, to 4,588.99.

The benchmark S&P has fallen for four straight sessions and nine of the past 11 days. It is down more about 4 percent from its last record high Dec. 29. The CBOE Volatility index was on track for a fifth day of gains.

Best Buy shares tumbled 14 percent as the worst performing S&P 500 component after the electronics retailer posted holiday sales results and said it expects same-store sales growth to be flat to negative in the first two quarters of its fiscal year.

Declining issues outnumbered advancing ones on the NYSE by 1,927 to 1,073, for a 1.80-to-1 ratio; on the Nasdaq, 1,980 issues fell and 666 advanced for a 2.97-to-1 ratio favoring decliners.

The S&P 500 was posting 21 new 52-week highs and 10 new lows; the Nasdaq Composite was recording 26 new highs and 79 new lows. (Editing by Bernadette Baum and Nick Zieminski)