Oct 19 (Reuters) - J.P.Morgan on Tuesday became the second brokerage in two weeks to cut its forecast for Apple Inc"s (AAPL.O) iPhone sales for the crucial holiday quarter as the global chip shortage and factory closures in Asia finally catch up to the technology giant. The brokerage trimmed its iPhone revenue estimate to $63 billion for the first quarter of fiscal 2022, which would be a yearly fall of nearly 4%, analyst Samik Chatterjee said in a note to clients. Last week, Needham said it expected iPhone 13 shipments to total 80 million units in the first quarter and cut its estimates for the holiday quarter by 10 million units citing supply chain issues including the chip shortage. For the fourth quarter, JPM expects iPhones to bring in revenue of $46 billion after selling 58 million units, marginally higher than Wall Street"s forecast of $41 billion. According to Refinitiv IBES, analysts are expecting about 45 million units for the holiday quarter and 79.4 million units in the first quarter. While Apple has weathered the supply crunch better than many other companies due to its massive purchasing power and long-term supply agreements with chip vendors, supply chain bottlenecks and lockdown in countries like Vietnam in the second half of the year are hampering its production timelines. Bloomberg News reported last week that the Cupertino, California-based company is likely to slash production of its iPhone 13 by as many as 10 million units due to the global chip shortage. read more Customers wanting an iPhone 13 are already having their patience tested with one of the longest wait times for the phone in recent years, analysts said. read more "We continue to see strong demand for iPhone 13 and 5G iPhone SE relative to low investor expectations to act as a catalyst, the timing of realization of which, although delayed on account of supply headwinds, is unchanged in magnitude," Chatterjee said. However, Apple said on Monday that its two new MacBook Pro models, that run on more powerful in-house chips, and new AirPods 3, will start shipping next week. read more Apple"s announcement of hardware innovations for the holiday season despite the chip shortage showed the company was flexing its supply chain muscles, Wedbush analyst Daniel Ives said.