Insiders at Calabasas commercial real estate brokerage Marcus & Millichap Inc. have sold 3.2 million shares of stock in a transaction that totaled more than $102 million, according to a regulatory filing.

The holdings were sold by Phoenix Investments Holdings, a Delaware limited liability company formed to hold 25 million shares received by co-founder and chairman George M. Marcus and other company shareholders when the company went public in October 2013.

The 3.2 million shares were sold Wednesday on the open market at an average price of $31.99. None of the proceeds went to the company. Phoenix also granted underwriters a 30-day option to purchase up to an additional 600,000 shares of common stock. Shares trade on the New York Stock Exchange.

The sale was disclosed in a filing with the Securities & Exchange Commission. Investors who own 10 percent or more of a company’s shares are required to disclose their transactions with the SEC.

Following the completion of Wednesday’s sale, Phoenix directly owns 21 million shares worth about $677 million – roughly half of the value of the company’s $1.25 billion market cap.

Citigroup, Barclays and Wells Fargo Securities were joint book-running managers. The securities were offered under the company’s shelf registration statement previously filed with the Securities and Exchange Commission.

Shares have risen steadily since the $12 pricing of the initial public offering, which raised $72 million. They closed on Friday up 98 cents, or nearly 3 percent, to $34.60.