(Close): US stock markets closed lower on Wednesday.

The Dow Jones Industrial Average fell 42.43 points or 0.25% to close at 16,633.

The technology-heavy Nasdaq dropped 11.99 points, or 0.28% to 4,225 and the S&P 500 slumped 2.13 points, or 0.11%, at 1,909.

Shares in the maker of Botox, Allergan, fell 5.4% after Canada's Valeant Pharmaceuticals improved its offer for the firm.

Valeant increased the cash part of its bid, which raised its offer by $7.6bn. Valeant shares fell 2.3%.

McDonald's was the biggest loser among Dow Industrial stocks. Shares lost 1.04% after the company raised the amount of cash it plans to return to investors.

McDonald's says it will return up to $20bn between 2014 and 2016.