US STOCKS-Wall St rises on gains in healthcare stocks
* Fed Chair Yellen to speak at 2:00 p.m. ET Wednesday
* Tobira Therapeutics rises eight-fold on Allergan deal
* DTS soars on $850 mln acquisition agreement with Tessera
* Indexes up: Dow 0.37 pct, S&P 0.31 pct, Nasdaq 0.32 pct (Adds details, comments, updates prices)
By Yashaswini Swamynathan
Sept 20 (Reuters) - Wall Street was higher on Tuesday, helped by gains in healthcare stocks, even as investors awaited monetary policy decisions from the U.S. Federal Reserve and the Bank of Japan.
Though the Fed is not expected to raise rates, Chair Janet Yellen's speech on Wednesday is keenly awaited for any clues about rate changes in the coming months.
Uncertainty surrounding the Bank of Japan is higher as investors have little idea of what tools it could use to achieve its inflation target.
"Investors have become more comfortable knowing that a Fed rate hike decision will be put off until future meetings, but there is more uncertainty with what Japan will do," said Paul Springmeyer, investment managing director at the Private Client Group, U.S. Bank in Minneapolis, Minnesota. Continuación...