Shares of ValueClick fell 10 percent early Tuesday after an analyst downgraded the stock and said one subsidiary now determines the company’s future.

PiperJaffray analyst Mark Zgutowicz said in a note to investors that ValueClick, an Internet advertising company in Westlake Village, relies too much on Dotomi, a subsidiary in Chicago. Dotomi uses data from a person’s past visits to websites to determine which ads the person sees. ValueClick bought Dotomi in August 2011.

Zgutowicz said ValueClick’s destiny now depends on Dotomi’s performance, and noted that ValueClick’s ad network business is slowing.

He lowered his recommendation on the stock to “neutral” from “overweight” and lowered his price target to $15 from $27.

By midday Tuesday, shares of ValueClick traded at $14.05, down $1.56 or 10 percent on the Nasdaq.