From the Associated Press:

Natural gas producer Quicksilver Resources Inc. is selling a 25 percent stake in its Barnett shale oil and gas assets to a subsidiary of Tokyo Gas Co. for $485 million.

Quicksilver said Friday that it will still operate the assets which are located in Texas. Shale is a rock formation thousands of feet underground. The company said that it expects to use proceeds from the sale to lower debt.

The transaction is expected to close on April 30.

On Monday Quicksilver reported that its fiscal fourth-quarter and full-year net income and revenue came in higher than it first reported in February.

The Fort Worth, Texas, company said that as it was preparing its final documents for the year, it determined that certain hedges did not qualify for hedge accounting at their designation dates. As a result, the unrealized gains and losses on these derivatives have been recognized in earnings rather than deferred.

The accounting change had a ripple effect on other parts of its financial statement and on its other quarters.

Quicksilver shares finished at $2.25 on Thursday. They have traded in a range of $1.62 to $5.97 over the past year. U.S. stock markets were closed Friday for the observance of Good Friday.