DoubleClick rose $2.06 at $17.31 by the 1 p.m. PST close of regular trading Tuesday. It hit a high of $17.50 earlier in the day.
Investors could take this as a positive sign. Although DoubleClick shares lost nearly 90 percent of their value last year--during a time of elevating concern about the viability of online advertising--the stock has gone up by almost 40 percent since Jan. 1 on positive fourth-quarter earnings.
The FTC's investigation began in February 2000 after the company announced plans to compile dossiers of consumer information, intended to better target advertisements to consumers as they surf the Web.
The government agency issued a letter Monday to DoubleClick's lawyers, notifying them of the investigation's end.
The investigation's close could break up the privacy storm clouds hovering over DoubleClick since it announced intentions to merge online and offline data. Although the ad network quickly reversed its position at the time, the investigation touched off a maelstrom of scrutiny from consumer advocates, media and legislators over data-collection practices on the Web.
Online storefronts and advertising networks alike were forced to react to heightened examination by bolstering their privacy practices and polices, as well as by hiring experts to defend the companies.
DoubleClick itself named a chief privacy officer in the past year and kicked off efforts to educate the public about online advertising practices.