The inquiries come as SEC officials have expressed concern about a possible corporate backlash against whistleblowers, the newspaper said. It couldn’t be determined how many or which companies were sent the letters or what penalties the SEC could potentially levy in the probe, the Journal said. Reuters could not immediately reach the SEC for comment. The 2010 Dodd-Frank Wall Street reform law gave the SEC the power to start a whistleblower program that lets the agency reward people who report misconduct, if that tip leads to the collection of more than $1 million in monetary sanctions.