Ameritrade ( AMTD) raised the low end of its second-quarter earnings guidance Friday despite a cooling in its customer trading volume. The Omaha, Neb., online brokerage expects to earn 16 cents to 19 cents a share in the quarter, compared with guidance it issued last month for earnings of 13 cents to 19 cents a share. Analysts surveyed by Thomson One Analytics expect the company to earn 18 cents a share in the quarter, which ends this month. Ameritrade had average daily volume of 197,000 trades in February, down from January's record 254,000 average daily trades, as investors' appetite for stocks began tapering after a nearly yearlong bull run. The company said it opened 39,000 new accounts and closed 11,000 in February, after opening a net 37,000 in January. The average margin balance among all its customers was about $3.5 billion in February, Ameritrade said, compared with $3 billion in January. Client margin loan balances totaled about $3.7 billion at Feb. 27, 2004, compared with $3.4 billion at Jan. 30. Ameritrade, along with rivals E*Trade ( ET) and Schwab ( SCH), have been major beneficiaries of stocks' rise over the last 12 months, with Ameritrade's shares running from below $5 to more than $15 before pulling back this week. On the Instinet premarket, Ameritrade was recently fetching $14.78, up 9 cents, or 0.6%, from their 4 p.m. EST Thursday close.