As part of an ongoing effort to reduce debt, Macerich Co. on Thursday said it had sold a 49.9 percent stake in two of its shopping malls to real estate investment management firm Heitman LLC.

Heitman, a Chicago firm with $20 billion in assets under management, paid the Santa Monica real estate investment trust more than $167 million in cash and assumed $161 million of the mortgages on Freehold Raceway Mall in Freehold, N.J., and the Chandler Fashion Center in Chandler, Ariz.

As it has in another joint venture announced last month for malls in Denver and New York, Macerich will continue to manage the properties.

Macerich last week said it had paid off $446 million of its 2010 term notes using capital raised through joint venture sales.

Shares were down $2.05, or nearly 8 percent, to $28.28 in midday trading on the New York Stock Exchange