Apple Inc. fell for the third day after analysts at Morgan Stanley cut their forecasts for iPhone shipments, adding to concern about the tech giant’s primary source of revenue ahead of quarterly earnings in May.

Morgan Stanley analyst Katy Huberty lowered her projections for iPhone shipments by 1 million in the quarter ending in March and 6 million for the current quarter. Huberty now sees shipments for fiscal 2018 of 210 million, down from an earlier estimate of 217 million.

The note comes a day after Taiwan Semiconductor Manufacturing Co. predicted current-quarter sales about US$1 billion less than analysts had projected. As Apple’s main chip supplier, TSMC’s tepid revenue forecast revived fears that the iPhone X, Apple’s flagship US$999 handset, may already be losing momentum a quarter after its release.

TSMC confirmed weakness at the very high end of the smartphone market, according to Neil Campling of Mirabaud Securities Ltd. The world’s largest chip foundry company had 63 days of inventory in the first quarter. "We have tracked TSMC inventory days for every quarter over the last decade and inventory days have never been higher," he wrote.

Apple fell 3.9 per cent Friday and is now down more than 6 per cent since Wednesday, while other big tech companies -- Facebook Inc., Amazon.com Inc., Netflix Inc. and Alphabet Inc. -- are higher.

OTR Global LLC also weighed in on Apple, saying the outlook for iPhone sales in China has deteriorated for the second quarter of 2018, as competition from Asian vendors intensifies.

Still, it wasn’t all bad news for Apple. Morgan Stanley’s Huberty also said to buy any dip in shares after second-quarter results, scheduled May 1, as the company will likely accelerate its capital return program.

And Apple has other levers to pull, Bank of America Merrill Lynch analyst Wamsi Mohan said in a note Friday. The company will pivot in coming years away from the "boom-bust of iPhone cycles" toward services, with products like the App store, iCloud, Apple Music, iBooks and Apple Pay offering "significant room to grow," he wrote.