AT&T Inc. T, +0.61% failed to provide requested documents to a Senate investigation of payments made to President Donald Trump's former personal lawyer Michael Cohen via a shell company in the months after Trump's election in 2016, according to a report on the probe. AT&T, Swiss drug company Novartis NVS, -1.31% , private-equity firm Columbus Nova, an investment company with ties to sanctioned Russian oligarch Viktor Vekselberga and Korea Aerospace Industries made payments totaling $4 million to Cohen, according to press reports and a memo released by Michael Avenatti, the lawyer representing Stephanie Clifford, a pornographic film actress known as "Stormy Daniels," who was paid $130,000 by the shell company to stay quiet about an alleged affair with Trump. "Novartis provided the Senators with documents reflecting the company's communication with Mr. Cohen, but declined to provide other documents requested by the Senators, including any documents reflecting internal communications regarding Mr. Cohen and his role with the company," said the report. "A similar letter was sent to AT&T, which did not provide all of the requested information. While AT&T made a number of assertions about their relationship with Mr. Cohen and why he was hired, the company failed to provide any of the requested documents." AT&T shares were down 2% in early trade, and have fallen 18.7% in 2018, while the S&P 500 SPX, +0.29% has gained 4.6%.