Evan Greenberg, the chief executive officer of insurer Chubb Ltd., said companies may find it difficult to obtain financing after central banks have propped up economic growth for years, likening their stimuli to a drug.

“We may be at the beginning of a great unwind in credit availability,” Greenberg said in an annual letter to investors. “If so, that bodes poorly for future growth and the interest rate outlook.”

Greenberg said that about $10 trillion in stimulus by central banks globally has spurred many companies to misallocate capital. Investors have fled to safer investments such as U.S. Treasuries and other assets, driving up the price of urban real estate and pushing down growth for companies doing business abroad, he said.

The economy has decelerated partially due to “global overcapacity and increase of capital caused by cheap money from years of central banks’ stimulus — a drug we should have been off of some time ago,” he said.

The Federal Reserve raised rates in December, ending years of near-record low interest rates. Officials have been debating how to tighten policy amid heightened global risks, and broadly agreed in a meeting last month to proceed cautiously.

Clashing Policies

“We see less-coordinated central bank policies with the Fed aiming to tighten but confounded by a strong dollar while the EU and Japan engage in continued monetary easing,” Greenberg said. “Many emerging economies are suffering at their own hand as well.”

Chubb propelled growth this year by combining with Ace Ltd. in a more than $29 billion deal, and the CEO said the insurer plans to use its funds to invest in the company instead of focusing on stock buybacks and boosting dividends. Conversely, one of the insurer’s largest rivals, American International Group Inc., has announced a plan to return $25 billion to shareholders over the next two years. Focusing on returning capital to shareholders is “hardly a strategy for long-term growth,” Greenberg wrote.

“We are eating our seed corn brought to you by the Fed,” Greenberg said about the impact of cheap money. “Central bank policies to stimulate growth following the financial crisis have in my judgment outlived their usefulness.”