South Portland-based corporate payment technology provider Wex Inc. said Tuesday that its board of directors has authorized a stock buyback program under which up to $150 million worth of the company’s common stock may be repurchased.

Company spokesman Rob Gould said the board authorization merely extends an existing buyback program that is about to expire. A buyback is when a company pays shareholders the market value per share to reclaim a portion of its ownership that was previously distributed among investors. Companies typically implement buyback programs when they’re doing well.

“Our existing authorization was expiring on Sept. 30, so this simply extends that authorization that is in place,” he said.

Wex may initiate buybacks from time to time until Sept. 30, 2021, through open-market purchases, privately negotiated transactions, block trades or otherwise, the company said in a statement. Buybacks are subject to the availability of stock, prevailing market conditions, trading price of the stock and the company’s financial performance, Wex said.

The buyback program does not obligate Wex to acquire any specific number of shares, and it may be discontinued or suspended at any time. The company is not scheduled to acquire any shares at this time, the release said.