WPP Share News (WPP)

March 29 (Reuters) - Shares of Acxiom Corp plunged27 percent on Thursday, after Facebook Inc said it wouldend its partnerships with several large data brokers who helpadvertisers target people on the social network.

The stock has now lost more than a third of its market valuesince Facebook's comments on Wednesday. It touched its lowest inmore than 1-1/2 years in early trading on Thursday.

Facebook is under pressure to improve its handling of dataafter disclosing that information 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.

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.

Shares of Acxiom were down 27 percent at $20.47 in earlytrading.(Reporting by Sonam Rai in BengaluruEditing by Saumyadeb Chakrabarty)