Investors are leaning on Santa Monica’s Macerich Co. to reconsider a buyout offer from rival mall operator Simon Property Group of Indianapolis.

Simon offered a final bid of $16.8 billion to Macerich last month, but Macerich executives rejected the officer, saying it was too low. Now, activist investor Land and Buildings and hedge fund Orange Capital, both in New York, are reportedly trying to get Macerich to work out a deal with Simon. Representatives from the two investment firms declined to comment, but a source familiar with the matter confirmed the firms would like Macerich to engage with Simon.

Orange Capital has recently acquired a nearly 1 percent state in Macerich, while Land and Buildings owns a smaller stake, according to the Wall Street Journal.

The two firms said Wednesday that they have formed an investment group “to advocate for change at Macerich Co.” and claim Macerich has made “egregious governance missteps” related to the company’s “refusal to meaningfully engage with Simon Property Group.”

Meanwhile, Macerich is focusing on its own acquisitions, announcing on Wednesday that it has teamed up with Pennsylvania Real Estate Investment Trust PREIT on a tentative agreement with the city of Philadelphia to redevelop a mall there. If approved by the city, the Gallery mall would be rebranded as the Fashion Outlets of Philadelphia at Market East after a two-year renovation.

Macerich has about 53 shopping centers with most located in California and Arizona. Simon and Macerich are respectively the first- and third-largest shopping mall owners in the country.

Macerich Company did not return calls for comment. The company’s shares closed the day at $82.30, up 2 percent.