Union Drilling Inc, Questcor Pharmaceuticals, Diageo Plc, Safeway Inc, Weatherford International Ltd, Caterpillar Inc, Dow Chemical Co and Deutsche Bank AG are among the companies whose shares are moving in pre-market trading Tuesday.

Union Drilling, Inc. (UDRL) stock surged 4.57 percent to $6.41 in pre-market trading. Union Drilling and Sidewinder Drilling Inc announced Tuesday that the two companies had entered into a definitive agreement and plan of merger pursuant to which Sidewinder would acquire all of the outstanding shares of Union Drilling common stock in an all-cash tender offer valued at approximately $242 million.

Questcor Pharmaceuticals, Inc. (QCOR) stock gained 2.10 percent to $19.48 in pre-market trading. The shares slumped more than 36 percent in regular trading Monday after the company announced that it had become aware of a U.S. government investigation involving the company's promotional practices.

Diageo Plc (DEO) stock gained 2.01 percent to $114.12 in pre-market trading. United Spirits Limited and Diageo confirmed Tuesday that DEO was in discussion with United Spirits and United Breweries (Holdings) Limited in respect of possible transactions for Diageo Plc to acquire an interest in United Spirits Limited.

Safeway Inc. (SWY) stock gained 1.94 percent to $16.25 in pre-market trading. The stock has a 52-week low of $14.73, a 52-week high of $23.16 and $3.82 billion in market capitalization.

Weatherford International Ltd. (WFT) stock plunged 3.21 percent to $12.67 in pre-market trading. The stock has a 52-week low of $10.85, a 52-week high of $18.33 and $9.94 billion in market capitalization.

Caterpillar Inc. (CAT) stock plunged 2.20 percent to $88.87 in pre-market trading after the company lowered its fiscal 2015 earnings guidance due to global economic growth forecast over the next few years. The world's largest earth moving equipment maker currently expects the fiscal 2015 earnings to be in a range of $12 to $18 per share, down from its prior estimation of $15 to $20 per share.

Dow Chemical Co. (DOW) stock declined 1.39 percent to $29.80 in pre-market trading. The stock has a 52-week low of $20.61, a 52-week high of $36.08 and $36.21 billion in market capitalization.

Deutsche Bank AG (DB) stock declined 1.13 percent to $41.97 in pre-market trading. The stock has a 52-week low of $27.03, a 52-week high of $52.54 and $38.95 billion in market capitalization.