Facebook (FB) representatives told congressional investigators on Wednesday that it has discovered it sold ads to a Russian company seeking to target American voters during the 2016 election, according to a report from The Washington Post. The social media giant traced about $100,000 to a firm with a history of pushing pro-Kremlin propaganda. The newspaper didn't name the Russian company.

The ads began in the summer of 2015 and lasted to May 2017. A small portion directly named then-Republican nominee Donald Trump and Democrat Hillary Clinton. Most, however, focused on divisive issues such as gun rights, immigration, LGBT rights and racial discrimination.

Facebook came under scrutiny after the election for its role in facilitating the spread of fake news stories and after initially distancing itself from the matter announced plans to take a deeper look at what happened.

An investigation this spring looking at purchasers of politically-motivated ads found that about 3,000 ads had digital footprints leading to the Russian company. Facebook also discovered 470 suspicious and probably fraudulent accounts and pages it believes to be operated out of Russia and linked to the company. Facebook chief security officer Alex Stamos said in a statement posted on Wednesday that the Menlo Park, Calif.-based company has shut down the accounts and pages identified.

The U.S. intelligence community concluded at the start of the year that Russia's interference in the 2016 election had included using paid social media trolls to spread fake news intended to sway public opinion. Questions have long been raised about how they knew who to target and where.

Stamos said about a quarter of the ads identified as tied to Russia were geographically targeted and more ran in 2015 than in 2016.

"We know we have to stay vigilant to keep ahead of people who try to misuse our platform," Stamos said.

Jim Cramer and the AAP team hold a position in Facebook for their Action Alerts PLUS Charitable Trust Portfolio. Want to be alerted before Cramer buys or sells FB? Learn more now.

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