Offshore oil rig operator Ensco says it will buy Pride International in a deal valued at about $7.31 billion.

Stockholders of Houston-based Pride International Inc. will receive 0.4778 newly issued shares of London's Ensco PLC plus $15.60 in cash for each share of Pride common stock. When the deal closes, Pride stockholders collectively will own about 38 percent of Ensco's outstanding shares.

The $41.60-per-share offer price is a 21 percent premium to Pride's closing price on Friday.

The deal was approved by each company's board of directors. It is expected to close as soon as the second quarter.

The estimated value of the combined company is $16 billion.

Pride shares jumped $5.57, or 16.2 percent, to $39.96 in premarket trading. Ensco shares fell $2.41, or 4.4 percent, to $52.