* All 10 S&P sectors in positive territory
* Energy sector leads, backed by oil prices
* Tesaro soars on success of cancer drug
* Indexes up: Dow 1.47 pct, S&P 1.59 pct, Nasdaq 1.87 pct (Updates to late afternoon)
By Lewis Krauskopf
June 29 (Reuters) - Wall Street tallied big gains for a second day on Wednesday as investors continued to scour for bargains and digest the fallout from Britain's stunning vote to leave the European Union.
The S&P 500 had recouped more than half of its losses from the two-day equities rout sparked by the British referendum, which had amounted to $3 trillion in lost value from global equity markets, according to S&P Dow Jones Indices.
The S&P energy sector jumped 2.4 percent, the top-performing group for a second straight day, supported again by higher oil prices.
Financials, which were beaten up in the wake of the vote, gained 2 percent, and all 10 sectors were in positive territory.
"It's not the end of the world and it never was the end of the world, and to have these kinds of reactions was ridiculous," said Jeff Weniger, senior portfolio strategist at BMO Private Bank in Chicago. "People are starting to come to terms with it, starting to realize there aren't any of these major material changes, at least on the surface."
The Dow Jones industrial average was up 255.99 points, or 1.47 percent, at 17,665.71, the S&P 500 gained 32.39 points, or 1.59 percent, at 2,068.48 and the Nasdaq Composite added 87.65 points, or 1.87 percent, at 4,779.52.
Wall Street's rebound in the past two days has coincided with a bounce in oil prices, which rose on Wednesday after a larger-than-expected drawdown in U.S. crude inventories.
"I think people are still using oil as kind of a proxy for a read on the global economy," said Chuck Carlson, chief executive officer at Horizon Investment Services in Hammond, Indiana. "If oil prices firm, that seems to be giving a little bit more breathing room that Brexit and everything else isn't going to just tank the global economy."
Adding to the positive sentiment, U.S. consumer spending rose for a second straight month in May on increased demand for automobiles and other goods. But there are fears Brexit could hurt confidence and prompt households to cut back on consumption.
Britain's vote could be a new drag on the U.S. economy at a time when momentum in the U.S. job market may already by slowing, Federal Reserve governor Jerome Powell said late on Tuesday.
Investors are still bracing for volatility in coming weeks amid uncertainty about how Britain will pursue its EU exit, with some pointing to more possible downside. The S&P 500 was within 17 points of its May 2015 record high last Thursday.
Tesaro soared 106.6 percent to $76.89 after the company's ovarian cancer drug met its main goal. The stock was the top percentage gainer on the Nasdaq.
NYSE advancers outnumbered decliners by a 7.38-to-1 ratio; on the Nasdaq, a 4.02-to-1 ratio favored advancers.
The S&P 500 posted 46 new 52-week highs and no new lows; the Nasdaq recorded 38 new highs and 33 new lows. (Additional reporting by Chuck Mikolajczak in New York and Yashaswini Swamynathan in Bengaluru; Editing by Saumyadeb Chakrabarty)