WPP Share News (WPP)

By Sonam Rai

March 29 (Reuters) - Shares of Acxiom Corp plungedas much as 34 percent on Thursday, after Facebook Incsaid it would end its partnerships with several large databrokers who help advertisers target people on the socialnetwork.

The stock has now lost nearly half of its market value sinceFacebook's comments on Wednesday that added to fears ofincreased scrutiny around how public data is handled and shared.

Facebook is under pressure to improve how it manages dataafter disclosing that information on about 50 million Facebookusers wrongly ended up in the hands of political consultancyCambridge Analytica.

The social network has for years given advertisers theoption of targeting their ads based on data collected bycompanies such as Acxiom. Facebook's website lists ninethird-party data providers that it has worked with, includingAcxiom, Experian PLC, Oracle Data Cloud,TransUnion and WPP PLC.

Arkansas-based Acxiom, which earns over $800 million a yearselling consumer profiles to the world's largest companies, saidlate on Wednesday it did not expect this change to impact itsrevenue or earnings for the year ending in March.

However, for fiscal year 2019, Acxiom expects total revenueand profitability to be hurt by as much as $25million.

"The immediate impact was small. Now the question is how fardoes Facebook react to its issues," First Analysis analyst LarryBerlin said.

"A lot of what (Acxiom) is doing is probably not wrong andprobably not at the core of the problem that Facebook has.Targeting consumers using data is sometimes very clean andsometimes it isn't."

Even with little raw data, third-party data providers likeAcxiom attempt to build detailed pictures of individuals'finances, relationships, personal interests and purchasingtastes.

These profiles power targeted advertising across theinternet, and can also be used to determine what politicalissues people are interested in and how they might vote.

"I welcome Facebook's announcement that it will be shuttingdown its partner category service, using third party data toinform targeted advertising," said Britain's InformationCommissioner Elizabeth Denham in a statement on Thursday.

WPP, Experian, TransUnion and Cisco did not immediatelyrespond to requests for comment.

Shares of Acxiom were down 32 percent at $19 by midday. Thestock touch its lowest in more than 2 years in early trading.

TransUnion fell nearly 1 percent, while WPP was downmarginally.(Reporting by Sonam Rai in BengaluruEditing by Saumyadeb Chakrabarty)