* Remain camp leads Brexit, say bookmakers
* Tesla falls after offering to buy SolarCity
* Adobe falls after forecast disappoints investors
* Indexes up: Dow 0.36 pct, S&P 0.39 pct, Nasdaq 0.48 pct (Adds details, changes comment, updates prices)
By Tanya Agrawal
June 22 (Reuters) - U.S. stocks rose in late morning trading on Wednesday, helped by a jump in healthcare stocks, even as investors awaited the outcome of Britain's referendum on its European Union membership.
Traders are guardedly optimistic about a "Remain" vote. Polls are extremely close but bookmakers point to betting patterns in favor of the U.K. remaining in the EU.
The S&P 500 health index jumped 1.34 percent after a report said Medicare spending levels did not exceed targets and did not warrant the formation of a cost-control board.
Bristol-Myers Squibb was up 2.6 percent and Celgene up 3.3 percent, providing the biggest boost to the sector.
The Nasdaq Biotechnology Index spiked 2.5 percent.
Investors are also keeping an eye on U.S. Federal Reserve Chair Janet Yellen's second day of testimony to Congress.
On Tuesday, Yellen played down the risk of a recession, but warned that the British vote on Thursday and a U.S. hiring slowdown posed risks to the economic outlook.
Yellen's comments pointed to a cautious central bank, ruling out a July rate hike.
International Monetary Fund Managing Director Christine Lagarde also said on Wednesday that the Fed should avoid "abrupt" interest rate moves and focus on stability in its monetary policy.
Trading volume remains thin as investors adopt a wait-and-watch approach.
"Today is a whole lot of nothing," said Art Hogan, chief market strategist at Wunderlich Securities in New York.
"We are clawing back some of the losses from last week and are in a bit of a holding pattern ahead of tomorrow's vote. I think if there is a "Leave" vote, then a July rate hike is definitely off the table and we might be looking at just one hike in December."
At 11:09 a.m. ET (1509 GMT), the Dow Jones industrial average was up 63.45 points, or 0.36 percent, at 17,893.18, the S&P 500 was up 8.2 points, or 0.39 percent, at 2,097.1 and the Nasdaq Composite was up 23.47 points, or 0.48 percent, at 4,867.24.
Eight of the 10 major S&P sectors were higher.
Data showed May home resales rose to a more than nine-year high as improving supply increased choices for buyers.
Tesla Motors was down 6.8 percent at $204.52 after the Elon Musk-owned electric car maker made an offer to buy his solar installation firm SolarCity in a deal worth as much as $2.8 billion. SolarCity was up 8.3 percent at $23.10.
Adobe Systems was down 4.9 percent at $94.83 after its second-quarter revenue and full-year revenue forecast just about met analysts' estimates.
FedEx fell 3.6 percent to $158, a day after the package delivery company reported a quarterly loss.
Advancing issues outnumbered decliners on the NYSE by 1,833 to 987. On the Nasdaq, 1,745 issues rose and 830 fell.
The S&P 500 index showed 25 new 52-week highs and three new low, while the Nasdaq recorded 41 new highs and 33 new lows. (Reporting by Tanya Agrawal in Bangalore; Editing by Don Sebastian)