Starboard Value has confirmed its stake in insurance broker Willis Towers Watson, saying shareholders must hold management to account for meeting targets.

Speaking at the Capitalize for Kids Investor Conference in Toronto, Starboard’s founder Jeffrey Smith said that Willis Towers continues to be a “significant value creation opportunity,” but poor execution and a failure to meet targets has meant the company has underperformed against its peers, and become undervalued, despite having no noticeable disadvantages to its peers.

In a presentation released at the conference, the activist cited Willis Towers’ underperformance versus rival insurance company Aon. “Over the past half-decade, Aon’s efforts to improve margins resulted in a ~900bp improvement in adjusted operating margins,” Starboard wrote. “We believe a similar playbook can be implemented at Willis Towers Watson.”

The activist, which did not disclose the exact worth of its stake, said that financial targets set by Willis Towers CEO Carl Hess at a September Investor Day were a “good start,” and said that Willis Towers could also could make available more working capital, improve free cash flow, and take on more debt, which would generate cash to launch share buybacks and return cash to shareholders through other means.

Smith said that if Willis Towers is able to meet its financial targets and take other steps to improve shareholder value, the company’s share price could almost double by 2024, with the activist placing a $456 per share target on the company.

“Shareholders must hold management accountable for meeting achievable targets,” Smith stated.

In September, the Wall Street Journal reported that both Elliott Management and Starboard had built stakes in Willis Towers, though the funds were taking a “wait and see” approach before taking action.