Lehman Brothers Holdings Inc. was posted slightly stronger-than expected results, but its shares fell 2.6 percent as investors worried about the investment bank’s subprime mortgage exposure. Lehman, the fourth-largest U.S. investment bank by market value, stated that net income rose to $1.15 billion, or $1.96 a share, for the three months ended February 28, from $1.1 billion, or $1.83 a share, a year earlier. According to Reuters Estimates these results beat out the average analyst estimates by only a penny. However, the company’s shares fell more than 3 percent, to $69.76, in early trading, hurt by concerns about how Lehman’s securitization business, among others, will be affected by recent high defaults in subprime mortgages. “Goldman Sachs yesterday had good results, but the market didn’t care, and their shares fell. And in the case of Lehman, you have more subprime exposure,” said Adam Compton, head of research for U.S. financial equities at RCM Global Investors in San Francisco.