Air Products and Chemicals (APD) shares soared on Monday following reports that activist investor Mantle Ridge has acquired a stake worth more than $1 billion in the industrial gas provider and plans to push for improvements at the company.

Shares of industrial gas manufacturer Air Products rose about 5% in postmarket trading after the Wall Street Journal reported that activist investor Mantle Ridge had built a stake worth more than $1 billion in the company.

Mantle Ridge, run by Paul Hilal, plans to push executives at the industrial gas manufacturer on succession planning for Chief Executive Seifi Ghasemi and for improvements to the company’s strategy and capital allocation,

Air Products shares are badly underperforming the S&P 500 for a second straight year, and the company has suffered from leadership upheaval.

Air Products (NYSE:APD) rose 2.7% in after hours trading after a report that activist investor Mantle Ridge has accumulated a more than $1 billion stake in the industrial gas maker. Mantle Ridge has been building its position in Air Products since March,