A shadow is falling over Silicon Valley, and some of its most promising startups are crumbling under the pressure.

Just this Wednesday, high flying microbiome startup uBiome announced it was filing for bankruptcy after months of controversy and federal investigations into its testing procedures and billing practices.

The startup, which claimed to test users' stool samples using cutting edge medical technology, had raised more than $104 million in private venture capital from top firms like 8VC and Andreessen Horowitz. Before filing Chapter 11 on Wednesday, the buzzy startup was worth more than $600 million, according to Pitchbook data.

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But as flame outs go, uBiome is hardly the exception to Silicon Valley's rule. In fact, the company was only the fourth largest to hit a wall so far in 2019. The top 11 startups that either filed for bankrtupcy or shut down entirely raked in more than $889 million in private venture capital during their lifetimes, and range from consumer robotics makers and blockchain startups all the way to comic book inspired monthly subscription boxes.

Although concentrated in California's Silicon Valley, startups around the country were not spared from the financial Grim Reaper. Two Maryland-based startups bit the dust, as did others in Virginia and Boston, Massachusetts.

Here are the 11 most valuable startups that have gone under so far in 2019, according to Pitchbook data.