PDC Energy Inc. is the latest U.S. exploration and production (E&P) company to come under attack by an activist investor, after Kimmeridge Energy Management Co. LLC announced last week that it has acquired more than 5% of the stock and wants it to generate more value for shareholders.

In a filing with the U.S. Securities and Exchange Commission, private equity firm Kimmeridge, which focuses solely on the unconventional upstream sector, said PDC’s shares are underperforming and trading at “a steep discount to intrinsic value.”

The E&P said in a response to the filing that its board has had “numerous discussions and meetings” with Kimmeridge about its concerns. Kimmeridge added that it would continue to engage with the company and push for better returns, lower costs and a cash dividend for shareholders. Kimmeridge also wants executive compensation tied to the company’s stock performance and greater scale in PDC’s core areas in the Denver-Julesburg Basin of Colorado and the Permian Basin’s Delaware sub-basin.

PDC is set to release its year-end earnings on Wednesday and host a conference call with financial analysts on Thursday. Kimmeridge said it wants to hear its concerns addressed then.

The private equity firm said it would be discussing its plans with other shareholders and wouldn’t stop short of exploring strategic alternatives such as a sale of assets or the company.

PDC appeared to reject the filing, noting that it has already announced a plan to cut year/year capital spending by $150 million in 2019, grow production 20% over the same time and generate positive free cash flow.

“PDC is open to the views and opinions of all shareholders,” the company said. “We take constructive suggestions seriously and regularly review the company’s portfolio, strategy and structure to drive value creation.” The company added that it remains “committed to acting in the best interest” of its shareholders.

The bulk of PDC’s production comes from the Wattenberg Field in northeast Colorado, where it has wrestled with midstream constraints that are expected to be alleviated later this year. It entered the Permian in 2016.

Kimmeridge, founded in 2012, has spent more than $112 million to acquire 5.1% of the company’s stock. The firm is putting pressure on PDC at a time when other onshore E&P operators across the country have faced similar investor activism.