Xiaomi Corp, the privately owned Chinese electronics company, and other Chinese firms have joined in a $40 million investment in the United States technology startup Misfit.

It is the first time that Xiaomi, the world's third-biggest smartphone manufacturer, has taken a stake in a US mobile-device maker.

Misfit, which claims to make the biggest-selling activity and sleep tracker in China, said on Tuesday it had raised new financing from Xiaomi, e-commerce company JD.com Inc and venture-capital firms GGV Capital and Shunwei.