Pulte Homes Inc. announced Tuesday that is founder and chairman, William J. Pulte, recently sold 760,000 shares of the company's stock (NYSE:PHM) "to satisfy margin calls related to loan agreements that involved family members and a charitable organization."

In its statment, the company said, "Due to recent volatility in the value of Pulte Homes shares, margin calls were triggered and Mr. Pulte sold shares to meet his contractual obligations."

Pulte himself added, "I never intended to sell these shares and I am very disappointed I had to at this time. I remain confident in our leadership team, our strong financial position and in the long-term prospect of our company."

Shares of Pulte have been highly volatile in recent weeks. The stock hit a 52-week high of $17.32 on Sept. 18, then slid down to a low of $6.91 on Oct. 24 in the wake of a broad-based selloff of builder stocks on Thursday, Oct. 23.

In its statement, the company warned that "further unforeseen volatility in the value of Pulte Homes shares could lead to additional activity in the future related to margin transactions."

Margin calls are triggered when the value of a leveraged investment portfolio falls below levels determined either by law or by agreement with the brokerage. Under Federal Reserve minimum requirments, when securities are bought on margin, the investor needs to put up 50% initially and then maintain a 25% maintenance margin on the account.

There have been recent calls from some economists for the Fed to lower margin requirements to help ease the financial crisis by limiting margin calls, which tend to further depress stock prices in a down market.