That's according to figures out over the weekend from research firm IDC.
It estimates Apple phone shipments dropped about 10% over the first quarter of this year.
That saw its market share slip to 17.3%.
The iPhone-maker appears to be suffering as rivals step up competition.
South Korea's Samsung launched new flagship models over the period, driving a strong rise in sales.
Its market share rose to almost 21%.
China also looks like a problem for Apple, with industry experts estimating its sales there were down by almost a quarter in the first six weeks of the year.
Some companies and government agencies are restricting use of its phones in the country over national security concerns.
Those moves mirror U.S. government restrictions on Chinese apps on security grounds.
Local brands are also upping their game.
Xiaomi is now closing in on Apple in third place, with over 14% of the global market, while Huawei is gaining ground too.
Its latest flagship phones have been hailed by Chinese media as a triumph over U.S. sanctions on the firm.
