The perfect mix of Halloween and Silicon Valley may have turned the simple black long-sleeve turtleneck into a hot commodity in the San Francisco Bay Area.

Several Bay Area retail chains in the are running low on, and even selling out of, the staple top for the fall season. Quartz first reported that Uniqlo stores in the area seemed to have run out of the sweater, and Business Insider has found that there are similar shortages at local Gap, H&M, Target, and Kohl's locations.

The black turtleneck has long been an icon in Silicon Valley, first for its association with the Apple cofounder Steve Jobs and more recently as the look of Elizabeth Holmes — the infamous cofounder and CEO of Theranos, the Silicon Valley-based blood-testing startup that was once valued at $9 billion before shutting down amid accusations of fraud.

Most of the photos you'll find online of Holmes show her in an all-black ensemble, with the same black long-sleeve turtleneck, often with a vest or suit jacket over it. Holmes readily volunteered in interviews that her self-described "uniform" — as well as her office furniture and penchant for secretiveness — was borrowed from Jobs, her idol. In a 2015 interview with Glamour, Holmes said she'd been wearing black turtlenecks since she was 8 years old and estimated she owned 150 black turtlenecks.

The look is both distinctive and easy to replicate, making it the ideal Halloween costume. Multiple outlets have offered their suggestions for how to dress like Holmes for Halloween. Turtleneck-clad Holmes lookalikes can be found on Instagram and across social media from Halloween celebrations this month.

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Quartz reported on Monday morning that black turtlenecks were not available for purchase at the five nearest Uniqlo stores to the reporter Daniel Wolfe's location in Oakland, California. Business Insider couldn't replicate those results: Uniqlo's website showed that the sweaters were in stock at most locations near our San Francisco office, though in "low stock" at two stores.

We did find, however, that several other retailers appeared to be having black-turtleneck shortages of their own.

The availability of black turtlenecks Monday afternoon near San Francisco. Gap

According to Gap's website, its cheapest medium-size black turtleneck was sold out Monday afternoon at eight of its 10 storefronts in the San Francisco area.

Additionally, only three of H&M's six locations in the area had the chain's $10 black turtleneck in stock, according to its website. While Forever 21's website doesn't offer an option for seeing whether items are in stock in brick-and-mortar stores, the retailer's black turtleneck is marked as a "going fast" item, with more than 1,100 purchases this week.

At Target, none of the 20 stores within 20 miles of San Francisco had a black turtleneck in stock. Some of the stores offered a pick-up date of November 2 at the earliest — after Halloween.

Holmes has become a household name in the past year, largely because of society's obsession with watching the downfall of alleged scammers. There's also been no shortage of media coverage, including a best-selling book, an HBO documentary, and two coming projects separately featuring Jennifer Lawrence and Kate McKinnon each playing the embattled Theranos founder.

But particularly in Silicon Valley, Theranos and Holmes have become symbolic of the downfalls of a system in which innovators are encouraged to move fast and break things. Before Holmes fell from grace, she was put on magazine covers, given a $4.5 billion net worth, and lauded as "the next Steve Jobs" — even before her blood-testing devices hit the market.

As BuzzFeed News' Alison Willmore wrote last year, Holmes has become "an illustration of Silicon Valley hubris" who is "the perfect fuel for our 24/7 take economy."

Additionally, Holmes is still spotted around San Francisco with her hotel-heir husband, Billy Evans, as she awaits her trial beginning next summer in San Jose, California.

That said, the apparent difficulties in purchasing a black turtleneck in the San Francisco area could simply be a function of the season. A black turtleneck is a simple, functional fall fashion staple that can easily be layered for additional warmth.

Still, it seems like too much of a coincidence that they're so hard to find, just days before Halloween.