Shares in ValueClick Inc. rose slightly Thursday morning after an analyst upgraded the online advertiser, saying the stock was now a bargain.

Citi Investment Research analyst Mark Mahaney upgraded the Westlake Village-based online ad seller to a “Buy” from a “Hold.”

“ValueClick still represents one of the broadest plays on the growth of Internet advertising and is the leading independent online advertising network,” Mahaney said in a research note. “As such, it should continue to benefit from what we view as a very favorable outlook for the growth of Internet advertising.”

Shares in ValueClick have been erratic as rumors grow and fade over the likelihood of a buyout. As one of the only independent, publicly traded online advertising companies, ValueClick could make a likely takeover target.

Also, the stock has been held back by an ongoing investigation by the Federal Trade Commission into its lead-generation business. Mahaney said the market has taken an “overly dim view” of the stock and that the share price has already been discounted.

Shares have dropped 30 percent since mid July. Shares were up 1.2 percent to $21.89 in afternoon trading Thursday on the Nasdaq.