NEW YORK (AFP) - US stocks rose Wednesday as a big Royal Dutch Shell acquisition and a large potential pharma deal offset concerns about earnings season and US monetary policy.

At the closing bell, the Dow Jones Industrial Average stood at 17,901.37, up 25.95 points (0.15 per cent).

The broad-based S&P 500 rose 5.51 (0.27 per cent) to 2,081.84, while the tech-rich Nasdaq Composite Index gained 40.59 (0.83 per cent) to 4,950.82.

Equities were lifted by Shell's announcement that it will buy BG Group for US$70 billion (S$95 billion) and by an offer from generic-drug giant Mylan to buy Perrigo for US$28.9 billion.

But stocks have also been kept from bigger gains by concerns the upcoming earnings season will be weak.

Also on the worry list: the chance of higher interest rates from the Fed. Minutes from the March meeting showed "several" policy makers favouring a rate hike in June with others seeing a liftoff later in 2015 or in 2016.

"There's just as many headwinds as tailwinds," said Michael James, managing director of equity trading at Wedbush Securities.