(Reuters) - Commodities trader and miner Glencore GLEN.L will buy back shares worth $1 billion in a move analysts said looked timed to soothe investor nerves just two days after a subpoena from U.S authorities rattled the stock.

FILE PHOTO: An employee of a private security company stands in front of the logo of commodities trader Glencore during the company's annual shareholder meeting in Cham, Switzerland May 24, 2017. REUTERS/Arnd Wiegmann/File Photo

Glencore’s shares suffered their worst day in over two years following Tuesday’s announcement of the U.S. subpoena. They are down about 18 percent this year and hovering near one-year lows.

“This does not seem a coincidence and ... suggests management also believes the recent price moves are extreme,” analysts at Barclays said in a note on Thursday.

Glencore shares rose on news of the buy-back program, which will run until the end of the year, and were up 3.9 percent at 0740 GMT, the top FTSE 100 index .FTSE gainers.

Mining companies have recovered from the commodity price crash of 2015-16 allowing them to return cash to shareholders via share buy-backs and higher dividends.

But Glencore is facing scrutiny from U.S. authorities who have demanded the company hand over documents about its business in the Democratic Republic of Congo, Venezuela and Nigeria as part of a corruption probe.

The documents requested from its U.S. division related to Glencore’s business in the three countries from 2007 to now.

“The buyback will help at the margin, but we do not expect Glencore’s valuation to increase before the Department of Justice investigation is completed, and that could take years,” Jefferies said in a note.

Some analysts believe the U.S subpoena could be a result of Glencore settling a mining row in the DRC with Israeli billionaire Dan Gertler, under U.S. sanctions since last year, by agreeing to pay royalties in euros.

The buyback will be split into two halves, one of 350 million pounds ($463 million) worth of shares to be bought by Aug. 7 and the remainder at the discretion of Citigroup, which is Glencore’s broker.

After outstripping rivals last year, Glencore’s share price has been hit by concerns about political risk in the DRC where it mines just over a quarter of the global output of cobalt.

The company has aggressively slashed its debt since 2015, when it faced a crisis.

($1 = 0.7552 pounds)