(The headline has been updated to clarify that Caltabiano is the co-founder of Cresco Labs.)

Joe Caltabiano, the co-founder of multistate marijuana operator Cresco Labs, on Monday announced he has resigned as president of the Chicago-based company, becoming the second high-profile founder to step down from a top post in less than a week.

Caltabiano will continue to serve on the board of Cresco, one of the largest vertically integrated marijuana companies in the United States.

Caltabiano, who co-founded Cresco Labs in 2013, didn’t give many details about why he is stepping down, other than to say in a statement that, “as a serial entrepreneur, I know it’s time for the next challenge.”

On Feb. 28, Andy Williams announced he was leaving Denver-based Medicine Man Technologies, a vertically integrated marijuana company he founded in 2014.

In a statement, Caltabiano listed his accomplishments as president:

Helped Cresco Labs gain access to major cannabis market in the country.

Launched and rolled out the Sunnyside national retail brand.

Sourced numerous multiple merger and acquisition transactions.

Developed more than a million square feet of cultivation space.

He also led several sale-leaseback transactions for Cresco Labs and a number of capital raises.