Billionaire philanthropist Eli Broad hasn’t made scheduled payments to the Museum of Contemporary Art in Los Angeles because the institution has $2.1 million in grants it hasn’t put toward exhibitions.

“Once our unspent exhibition funds have been used, we will make additional payments,” said Karen Denne, spokeswoman for the 79-year-old founder of KB Home (KBH), in an e-mail.

The missed payments come at a time when concerns over finances at the museum have resurfaced after four prominent artists quit MOCA’s board last month.