Shares in Countrywide Financial Corp. fell to a 4-year low Friday after billionaire investor Warren Buffett said he “never came close” to buying shares in the Calabasas-based lender.

Reports surfaced in August that the chairman of Omaha-based Berkshire Hathaway Inc. might buy a stake in the struggling lender. The reports said that Buffett had been increasing his stake in financial services companies with significant exposure to the mortgage market at the time. He was quoted on CNBC saying the worsening credit and housing markets may present some “real investment opportunities.”

Buffett said in an interview late Thursday on Fox Business Network that he never bought any Countrywide stock, and that the company lacked a comprehensive recovery plan that might have attracted him.

This news comes after Securities and Exchange Commission said it opened an informal inquiry into stock sales by Countrywide Chief Executive Angelo Mozilo after North Carolina’s State Treasurer raised concerns about the timing and frequency of Mozilo’s trades.

Shares in Countrywide sank 6.5 percent to $15.45 in afternoon trading Friday on the New York Stock Exchange, marking the stock’s lowest price since April of 2003.