A Wall Street analyst lays out a bleak worst-case scenario where coronavirus disrupts a 32% chunk of Apple's business

• If coronavirus-related disruptions to Apple's supply and demand continue past June, new product launches in September and its Christmas selling season would come under threat, Laura Martin of Needham wrote in a Tuesday note.
• The two key sale events have made up about 32% of Apple's annual revenue over the last three years, according to Martin.
• So far, Martin assumes Apple's coronavirus-related issues will cease before June 1. But that assumption may prove to be "too optimistic," she wrote.
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If the coronavirus outbreak continues, it could turn into a months-long saga for Apple and damage one of its major businesses, according to one Wall Street firm.

On Tuesday, Needham analyst Laura Martin lowered her earnings expectations for the technology giant following the company's February 17 announcement that it would miss its March quarter revenue guidance due to the negative impact of the coronavirus in China.

But the coronavirus, called COVID-19, could weigh on Apple revenues for even longer, according to Martin.

If coronavirus-related disruptions to Apple's supply and demand continue past June, new product launches in September and its Christmas selling season would come under greater threat, Martin wrote. Over the last three years, the autumn launches and holiday season sales have made up about 32% of Apple's annual revenue, according to the note.

If Apple's December quarter is disrupted, both the full years 2020 and 2021 would be negatively impacted because of the company's fiscal calendar, Martin wrote.

"Investors would be less likely to look through a weak FY20, we believe," said Martin.

So far, Martin has lowered only unit sales and revenue estimates for the quarters ending in March and June, which will be the most hit by the coronavirus epidemic. Martin's estimate assumes that coronavirus will stop disrupting supply and demand before June 1, and thus not negatively impact Apple's quarters that end in September or December.

But, "this assumption may prove to be too optimistic," she wrote. Martin maintained a "buy" rating and $350 price target on shares of Apple.

Apple has gained 1.5% year-to-date through Monday's close.