While investigators balk at revealing their sleuthing secrets, one main weapon is to look back at the trading activity that preceded major corporate announcements.

For example, the corporate announcements sent to users via email are usually written in English, Greek, and Greeklish.

News events and corporate announcements often drive this market volatility, so traders must be available and ready to respond at a moment's notice.

Any corporate announcement that reverses decades of business practice and entrenched philosophy, as this one did, is breathtaking.

Often, the back-to-back corporate announcements required everyone to scurry clear across the exhibit floor to get a seat at the next press conference.

Most of the corporate announcements are issued in press releases or during the conference calls and are summarized at websites.

No economic report or corporate announcement caused the turn.

A corporate announcement gave as reasons "the general business climate and the proliferation of newer and more modern competitors."

But others say recent corporate announcements of steep reductions in capital spending, plus faltering sales and profits among technology companies, suggest there is something to the notion.

Mr. Brink went on "an extended leave of absence" two weeks ago without any internal or external corporate announcement.