It may be a while before we see commercials about day traders buying islands, but there is little doubt that the retail investor is back. Yesterday, Ameritrade (NASDAQ:AMTD) reported its fiscal first-quarter results -- and that was a short-seller's nightmare.

For the quarter, the company generated net income of $71.9 million or $0.17 a share, up from $22 million or $0.05 a share last year. Revenues surged 25% to $226.4 million.

With the clients hungry for action, pumping in $11.5 billion in cash for the quarter, it should be no surprise that Ameritrade upped its guidance. For fiscal year 2004, the company expects to earn between $0.49 and $0.79 a share, compared to previous guidance of $0.37 to $0.59.

As much as a rallying market has helped, Ameritrade has also had a laser focus on reducing its cost structure, while at the same time, adding features and services. The firm also made several gutsy acquisitions, including Bidwell & Co. and Datek.

Last quarter, Ameritrade averaged 175,000 trades a day. And it is ramping significantly. Thus far in 2004, the daily average is about 250,000.

With a rising stock price, Ameritrade has currency to make deals. One speculation is a purchase of TD Waterhouse, part of Toronto Dominion Bank (NYSE:TD). However, as revealed through its recent talks with E*Trade (NYSE:ET), TD appears to want to maintain control, and Ameritrade does not need to capitulate on this.

In the world of online investing, Ameritrade is a pure play, which makes the stock very enticing for momentum investors. And to be sure, if the bull market continues apace, there is likely a bit of earnings-per-share momentum ahead.

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Tom Taulli is the author of six books on investing, including The Complete M&A Handbook (Random House). You can reach him attom@taulli.com.