* TSX ends down 1.2% at 20,439.87

* Financials lose 1.7%

* Energy falls 2%; oil settles 2.2% lower

April 25 (Reuters) - Canada's main stock index fell on Tuesday by the most in nearly six weeks as commodity prices dropped and investors grew more worried about the health of the U.S. regional banking sector.

The Toronto Stock Exchange's S&P/TSX composite index ended down 236.87 points, or 1.2%, at 20,439.87. It was the biggest decline for the index since March 15, following a steady climb higher in recent weeks.

U.S. stocks also fell as the quarterly results of some companies raised concerns about a slowing U.S. economy and First Republic Bank disclosed it lost more than half its deposits during last month's banking crisis.

"I think the worries about the pile of earnings coming up this week as well as the First Republic drop kind of scared everybody," said Barry Schwartz, portfolio manager at Baskin Financial Services.

"We just got a little too comfy and cozy and needed a shot in the arm, a little wake up call."

The Toronto market's financials sector, which accounts for 28% of the index's weighting, fell 1.7%, tracking declines in U.S. bank stocks.

Energy lost 2% as oil settled 2.2% lower at $77.07 a barrel, while the industrials group was down 1.8%.

Industrials were pressured by a near 4% decline in the shares of Canadian National Railway, giving back some recent gains, after the company reported quarterly results.

Utilities was the only major sector to end higher, gaining 0.3%, as bond yields fell. (Reporting by Fergal Smith; Additional reporting by Shristi Achar A in Bengaluru; Editing by Josie Kao and Lisa Shumaker)