"The volatile stock market may provide all the risk that most investors can stomach, but some Wall Street investment banks are making much more daring bets: pumping venture capital into fledgling Internet companies whose initial public offerings may be years away.</br></br>Traditionally, Wall Street's leaders have avoided venture investing, leaving it to specialized boutiques that raise money from universities, wealthy individuals and others. But with many venture funds lately earning 50% or more a year, securities industry heavyweights such as Goldman, Sachs & Co. and Morgan Stanley Dean Witter & Co. are pushing their capital into venture investments ranging from biotechnology to telecommunications.</br></br>Some of the most hectic action involves tiny, money-losing Internet enterprises that investment bankers hope will be the next Yahoo! Inc. or Amazon.com Inc.</br></br>Executives of closely held Internet companies are watching this stampede with delight. In May, Ross Garber, chairman of Vignette Corp., came to New York to raise $7 million of venture-capital equity for his Austin, Texas, Internet-software company. After huddling with Goldman, Morgan Stanley and three other firms, Mr. Garber realized his sights were too low.</br></br>""We ended up raising $14.3 million, including $10 million from the investment banks, and we could have gone much higher,"" Mr. Garber says. ""I had bankers calling me at home on weekends, threatening my future livelihood if I didn't let them in for a bigger stake."""