Grubb & Ellis Co., a struggling Chicago real-estate-services company, said its chief executive, Scott D. Peters, has resigned, about seven months after taking office.

Independent Director Gary H. Hunt will be interim CEO while the company searches for a permanent successor.

Mr. Peters' resignation follows that of Anthony Thompson, who resigned as chairman in February, and Robert Osbrink, who resigned in June as executive vice-president.

Mr. Peters took over as chief executive of Grubb & Ellis when the company was acquired by NNN Realty Advisors Inc. in a reverse merger last December. Before the acquisition, Mr. Peters had served as chief executive of NNN, a commercial real-estate asset management and services firm in Santa Ana, Calif.

Shares of Grubb & Ellis have plunged 49% since the beginning of the year. On Friday, they rose about 1.6% to $3.13, in 4 p.m. trading on the New York Stock Exchange. The company posted a first-quarter net loss of $5.9 million, compared to a profit of $3.6 million a year ago, dragged down by charges related to the write-off of the firm's investment in Grubb & Ellis Realty Advisors, and merger-related costs.

In 2006, the firm created Grubb & Ellis Realty Advisors, which raised $143 million in a "blank check" initial public offering, in a bid to enter the investment management business. But in March of this year, Grubb & Ellis Realty failed to get 80% of its shareholders' approval -- an SEC requirement -- for its first acquisition of three buildings, partly because of the change in the credit environment. The firm had to return the money to investors.

The firm's weak performance prompted Mr. Thompson, its former chairman, to file a complaint with the Securities and Exchange Commission late last month. Mr. Thompson, the second-largest shareholder of Grubb & Ellis with a 13.9% stake, was previously chairman of NNN Realty. C. Michael Kojaian, the former chairman of Grubb & Ellis and now a member of the board, is the largest shareholder, holding an approximate 20% stake.

"In the recent months since I left the board, Grubb & Ellis has announced poor results, been wracked by management turnover, and suffered an expensive and embarrassing setback when (Grubb & Ellis Realty Advisors) unceremoniously failed," wrote Mr. Thompson.

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