Boeing Co has told suppliers it will resume production of its best-selling 737 jets at a rate of 52 aircraft per month in February 2020, then stepping up to a record 57 jets monthly in June, three people familiar with the matter told Reuters.

Boeing told more than 100 suppliers during at least one Web meeting July 30 that the new schedule depended upon regulators approving the 737 Max to fly again commercially in the fourth quarter, one of the people said.

Shares of Boeing, the largest U.S. exporter, with about 145,000 employees, were up 4.5 percent at $355.18.