Microsoft chairman Bill Gates, co-founder Paul Allen, and other insiders have sold about $420 million of their stock in the software company in less than a month, filings with the Securities and Exchange Commission show.

The executives have sold about 2.8 million shares so far, with Gates' sales estimated at 800,000 shares.

The shares were sold before the company announced a two-for-one stock split on Dec. 9 .

Gates, whose sales currently represent just a fraction of his shareholdings, sold between Nov. 1 and 14 at prices ranging from $137.50 to $148.4375 each.

At the end of the month, he owned 139.1 million shares, or 278.2 million shares adjusted for the split.

Allen sold 1.905 million shares at prices ranging from $142.00 to $157.50 each between Nov. 8 and Nov. 22.

Allen held 50.998 million shares at the end of the month or 101.996 million shares adjusted for the split.

Other Microsoft insiders who reported sales during the month included Jon Shirley, Bernard Vergnes, Joachim Kempin, Brad Silverberg and James Allchin. Sales of some of these executives were made after they exercised options for shares.

Industry insiders attributed the sell-off to a number of factors that include the wide spread acceptance of Sun's Java language, sluggish suite sales, and the anticipation of the rapid deployment of cable services such as the @Home cable service.