Four MarketWatch.com ( MKTW) executives have received subpoenas from the Securities and Exchange Commission for their stock trading records as part of an investigation of former columnist Thom Calandra. Marketwatch spokesman Dan Silmore said Wednesday that at least one of those executives -- Editor in Chief David Callaway -- says he hasn't owned any stock other than MarketWatch during his five years with the company. The SEC also has subpoenaed the records of CEO Larry Kramer, Chief Technology Officer Jamie Thingelstad and Executive Vice President Bill Bishop, according to the company. The SEC is seeking records from March 2003 to December 2003, the period when Calandra was writing an investment newsletter. Calandra, a senior columnist and founding editor, resigned in January after refusing to turn over his personal trading records to MarketWatch in the wake of the SEC's investigation, launched in December. "We do not know why the SEC selected these individuals," Doug Appleton, general counsel of MarketWatch, said in a statement. "We can only surmise that it's because each either had management supervision of Thom Calandra or The Calandra Report or had potential access to The Calandra Reports prior to their publication." Both the SEC and MarketWatch are investigating Calandra, who as a columnist was allowed to own shares of the companies he wrote about. For instance, Calandra owned shares of two affiliated companies, Ivanhoe Energy and Ivanhoe Mines, that he regularly touted in his newsletter, and once flew to China and Mongolia at the expense of the latter. MarketWatch has stated publicly that its own probe has turned up no evidence Calandra traded ahead of his own columns, but has conceded the probe is incomplete without his personal trading records. Appleton said that MarketWatch also has no information that any of the four executives ever traded on nonpublic information communicated by Calandra.