Activist investor Elliott Investment Management has built a $1 billion stake in Phillips 66 and plans to push for two board seats.

Elliott sent a letter to the Houston-based fuel refiner’s board saying it sees a path for it to boost the stock price by about 75% by improving execution, restoring trust with investors and other measures, according to a statement Wednesday. Elliott did not call for ousting Phillips 66 Chief Executive Officer Mark Lashier.

“Mr. Lashier and the rest of the management team deserve investor support so long as they demonstrate meaningful progress against these targets,” Elliott said in the statement. “At the same time, we find the market’s skepticism to be understandable, and we believe the Board must take several steps to reassure investors that Phillips 66 is in the best possible position to achieve its value-creation potential.”

Shares of Phillips 66 rose as much as 5% before the start of regular trading in New York. The news was first reported by CNBC.

Elliott, based in West Palm Beach, has a long record of taking stakes in energy companies and pressing for changes.

If Phillips 66 fails to improve its performance and meet its 2025 targets, Elliott said the company could follow a similar path as Marathon Petroleum Corporation. In 2019, Marathon faced months of pressure from investors including Elliott and D.E. Shaw & Co. calling for sweeping changes. The activist campaign ultimately led to Gary Heminger stepping down as CEO after 45 years at the company.