Morgan Stanley Dean Witter & Co. said its fiscal first-quarter net income rose 21%, as strong gains in investment banking and asset management overcame a drop in profit from its credit card business. The nation's largest securities firm reported net income of $691 million, or $1.10 a share, up from $571 million, or 91 cents, pro-forma, for the year-earlier period. The results beat Wall Street's forecast of $1.06 a share. The company, formed in last year's merger of Morgan Stanley Group Inc. and Dean Witter, Discover & Co., returned 20.1% on equity for the latest quarter, ended Feb. 28, down from 20.7% a year ago. Net revenue rose 16% to $4.04 billion. Lehman Bros. Holdings Inc. and Goldman Sachs Group reported strong profits earlier in the week. Morgan Stanley stock fell $2.56 to close at $73.13 on the New York Stock Exchange.