OSLO (Bloomberg) — Bermuda-based Seadrill Ltd., the Norwegian oil-rig company started by billionaire John Fredriksen, fell nine percent in Oslo trading after saying it will book a $615 million loss on its investments in the fourth quarter.

The charge relates to holdings in Pride International Inc., Scorpion Offshore Ltd. and SapuraCrest Petroleum Bhd., the company said yesterday. Losses of $687 million on the investments in third quarter were never charged to the income statement, Seadrill also said.

"The share prices improved somewhat from the reporting date for the third quarter results to December 31, but were still significantly lower than when the positions were acquired," Seadrill said. The company will also post a $35 million loss on a total return swap on its Treasury shares and a $160 million charge from interest rate swaps in the quarter.

Seadrill fell to 51.6 kroner, extending a 9 percent drop on February 20 and valuing the company at 20.6 million kroner ($3 billion).

The company will report complete earnings on February 26.