Bolt Threads, a US-based high-performance fabrics developer backed by conglomerate Nan Fung, is seeking $106m in series D funding, according to a regulatory filing.
The company had secured $56.8m as of October 23, and TechCrunch identified venture capital firms Formation 8 and Foundation Capital as participants in the round.
Founded in 2009 as Refactored Materials, Bolt Threads is creating spider silk at industrial scale using microorganisms in order to create highly durable textiles. The material is stronger than polytetrafluoroethylene – commonly known as Teflon – but very soft.
The company, which had operated in stealth until mid-2015, introduced its first product, a necktie that costs $314, in March this year.
Bolt Threads had previously raised a total of $90m in equity funding, with Nan Fung participating in a $50m in a series C round in May 2016 led by Formation 8 that included Innovation Endeavors, Alafi Capital, East West Capital, Foundation Capital and Founders Fund.
Foundation Capital, Founders Fund, Formation 8 and Alafi Capital had also backed Bolt’s $32.3m series B round, though a date for that round has not been disclosed. Bolt Threads has not revealed details about its series A funding.