Tesla — Shares of Tesla popped nearly 3% after Canaccord Genuity upgraded the stock to buy, citing Tesla's battery innovations.

Nuance Communications — Nuance's share price rallied more than 16% in midday trading after Microsoft announced that it will buy the speech recognition company for $56 per share, about 23% above where its stock closed on Friday.

Alibaba — The U.S.-traded shares of the Chinese internet giant jumped more than 9% after Chinese regulators hit the company with a $2.8 billion fine.

Chipotle – The chain restaurant's share price rose more than 1% after Raymond James upgraded the stock to outperform from market perform.

The Wall Street firm said it sees "modest" stock price upside for Plug Power.