Shares of Whiting Petroleum falls sharply as it plans to sell 35 million shares to pay debt

Shares of Whiting Petroleum fell sharply Tuesday, a day after the company said it would sell its shares and senior notes to pay down debt related to its $6 billion acquisition of Kodiak Oil & Gas.

The oil and gas company said late Monday that it will offer 35 million of its shares and said underwriters had a 30-day option to purchase an additional 5.25 million in shares. The stock offering could bring Whiting more than $1.5 billion, based on its stock's closing price of $38.39 on Monday.

In addition, Whiting said it will sell $1.75 billion in senior notes. About $1 billion are due in 2020 and $750 million are due in 2023.

Whiting, based in Denver, completed its acquisition of Kodiak in December.

Shares of Whiting Petroleum Corp. dropped $7.83, or 20.4 percent, to $30.56 in premarket trading Tuesday. Its shares are down about 44 percent in the last 12 months.