Securities regulators have stepped up their investigation of mortgage giant Countrywide Financial Corp. and its former chief executive, Angelo R. Mozilo. Bank of America Corp., which acquired Calabasas-based Countrywide last month, said in a regulatory filing Thursday that the Securities and Exchange Commission was conducting a formal inquiry of the lender and that it had responded to subpoenas from the federal agency. The filing doesn’t say what the SEC is looking at, but people close to the probe say it represents an escalation of an informal investigation launched last year and is focused on whether Mozilo violated insider-trading law and whether Countrywide’s financial disclosures misled investors. For the full story visit www.latimes.com/business/la-fi-countrywide8-2008aug08,0,998095.story