Doubleclick (DCLK) , the online advertising company that was one of the major beneficiaries of the Internet boom — it’s stock once traded over $125 a share — noted in its most recent 10-Q that it had received a grand jury subpoena in October from U.S. Attorney James Comey. Doubleclick didn’t provide many details, other than to say that it had to do with “certain vendors that provided services to Doubleclick between 1999 through 2001”. Doubleclick says it is doing its own internal investigation and has found instances of overpayments and what it describes as “inappropriate payments” to vendors, which sounds like corporate speak for kick-backs. Comey has had a special grand jury sitting for awhile now whose sole purpose is to delve into corporate fraud — they’re the ones who indicted Martha Stewart back in May. Whatever Comey is looking at, it doesn’t seem to concern the folks at Salomon Smith Barney. On Wednesday, an analyst upgraded the stock from a sell to a buy.