NEW YORK (Reuters) -Activist investment firm Kimmeridge Energy Management has taken a stake in U.S. shale producer Devon Energy ( DVN ), according to a stock market filing released on Friday.

THE DETAILS

Kimmeridge owned 5.66 million shares in Devon as of the end of September, the filing said. That would equate to an approximately 0.9% stake in Devon, according to Reuters calculations, and make it Devon's 14th-largest shareholder, according to data provider LSEG.

Devon shares fell 1% in the opening 30 minutes of trading on Friday, amid a broader market sell-off, giving the company a market value of around $22 billion.

The 13F filing from Kimmeridge did not detail anything beyond the number of shares held at the end of the third quarter, and whether Kimmeridge has since increased or decreased its position. The filing came at the deadline for investment firms to reveal their holdings in public companies as of September 30.

When approached by Reuters, Kimmeridge declined comment. Devon did not respond to a comment request.

THE PLAYERS

Oklahoma City-based Devon is one of the larger independent U.S. shale producers, with operations in multiple formations including the Delaware portion of the Permian basin covering Texas and New Mexico, the Eagle Ford of South Texas and Oklahoma's Anadarko basin.

The company's shares have gained 4% year to date, in line with the performance of the S&P Energy index.

Among the best-known activists within the oil and gas industry, Kimmeridge has in recent years pushed energy companies for better governance practices, prioritizing shareholder returns over expansive drilling programs, and consolidation to achieve economies of scale.

Kimmeridge said on November 4 it owned a stake in Devon peer Coterra Energy ( CTRA ), and was pushing for leadership changes and the sale of its Appalachia and Oklahoma operations to focus on Coterra's Delaware basin holding.