* Shares fall 10 pct in Monday trade
* Q2 earnings fell 84 percent, shy of estimates
* Adjusted Q2 earnings rose 30 pct before charges
NEW YORK, Aug 8 (Reuters) - Stifel Financial Corp (SF.N) on Monday said second-quarter profit fell 84 percent as the investment bank and brokerage absorbed charges related to a lawsuit and a regulatory probe as well as costs related to its Thomas Weisel takeover last year.
The St. Louis-based investment bank, which bought Thomas Weisel Partners Group last year, said profit for the quarter fell to $3.42 million, or 5 cents a share, from $21.1 million, or 40 cents, in the year-earlier period.
Excluding charges, Stifel said profit rose 30 percent to $31.3 million, or 50 cents a share. Quarterly revenue increased 9.4 percent to $358.9 million.
Analysts on average forecast 54 cents a share in earnings, according to Thomson Reuters I/B/E/S estimates.
Shares of Stifel closed at $29.48, down nearly 10 percent, as investors unnerved by the Standard & Poor's downgrade of the U.S. sovereign credit rating fled stocks for the safety of bonds. (Reporting by Joseph A. Giannone; Editing by Steve Orlofsky)