* CBS shares jump after Supreme Court ruling
* Monsanto rallies on outlook and stock-repurchase plans
* U.S. economy shrank in Q1; durable orders fall
* Dow up 0.3 pct; S&P 500 up 0.5 pct; Nasdaq up 0.7 pct (Updates close with volume)
NEW YORK, June 25 (Reuters) - U.S. stocks rose on Wednesday, led by drugmakers, while a Supreme Court ruling lifted the shares of major broadcasters.
Shares of Bristol-Myers Squibb Co shot up 3 percent to $49.73. The rally came a day after the drugmaker said a late-stage trial testing its immunotherapy nivolumab in advanced melanoma patients was halted early after it was determined that the drug was likely to prolong survival.
Pfizer gained 1.7 percent to $29.80, Merck & Co. rose 1.6 percent to $58.86, and the S&P healthcare index ended 1.1 percent higher, giving the S&P 500 its biggest boost.
Shares of CBS jumped 6.2 percent to $62.48 after the U.S. Supreme Court ruled that online TV startup Aereo Inc violates copyright law by using tiny antennas to provide subscribers with broadcast network content via the Internet. Comcast Corp shares rose 1.1 percent to $53.21. The Walt Disney Co, which owns ABC News, gained 1.5 percent to $83.90 and buoyed the Dow.
The S&P 500's gains followed two days of losses, putting the index on track for a decline of 0.2 percent for the week.
"You do hear people talking about us being in some kind of a bubble, but I do not see that at all," said Bryant Evans, an investment adviser and portfolio manager at Cozad Asset Management, in Champaign, Illinois. "The stock prices are reflecting reasonable valuations."
The Dow Jones industrial average rose 49.38 points or 0.29 percent, to 16,867.51. The S&P 500 gained 9.55 points or 0.49 percent, to 1,959.53. The Nasdaq Composite added 29.40 points or 0.68 percent, to 4,379.76.
Monsanto Co also boosted the S&P 500. The stock climbed 5.1 percent to $126.73 after the world's largest seed company raised the low end of its full-year outlook and said it plans to offer debt to help finance a $10 billion stock buyback.
More merger news also helped the healthcare sector. Medical Action Industries surged 93.5 percent to $13.68 on its heaviest one-day volume ever after Owens & Minor Inc agreed to buy the supplier of disposable medical products for about $208 million. Owens rose 1.5 percent to $35.38.
On the downside, shares of refiners declined after U.S. officials allowed energy companies to export light crude oil, or condensate, after it has been minimally processed. Valero Energy , down 8.3 percent at $51.35, was the S&P 500's biggest percentage decliner, followed by Marathon Petroleum, down 6.3 percent at $80.97.
The major indexes slipped at the open after the economic data, but investors quickly moved on. The U.S. economy contracted in the first quarter at an annual rate of 2.9 percent, the sharpest drop in five years, though activity was affected by a harsh winter, and there are indications that growth has since rebounded. In another negative data point, U.S. orders for durable goods unexpectedly fell 1 percent in May.
About 5.7 billion shares changed hands on U.S. exchanges, slightly higher than the 5.6 billion average for the month to date, according to data from BATS Global Markets. (Editing by Nick Zieminski and Jan Paschal)