Online broker

Datek Online

said Monday that third-quarter trades fell by about 6% to 97,638 a day from 103,825 in the second quarter as retail investors pulled back with the market's slide.

The decline in trading activity during the third quarter was expected, with many analysts betting that online brokerages would post trading volume declines of about 10%.

E*Trade

(EGRP)

is expected to report its results Friday, with

Charles Schwab

(SCH)

TheStreet Recommends

expected next week and

Ameritrade

(AMTD) - Get Report

the following week.

Last week,

Knight Trading

(NITE)

, which executes trades for customers including Ameritrade and E*Trade,

issued an earnings warning. The Jersey City, N.J., firm said its earnings fell short of expectations in part because fewer individual investors traded stocks.