US-based wearables firm Misfit has raised $40 million from Xiaomi, e-commerce company JD.com and two venture-capital companies.

Xiaomi’s investment is the first time the fast-growing Chinese smartphone maker has taken a stake in a US technology firm, Reuters said.

Xiaomi, until recently the third largest smartphone maker in the world before being displaced by the $2.9 billion Motorola/Lenovo deal, has invested in numerous Chinese gadget suppliers to expand its focus beyond smartphones, which are increasingly becoming commoditised.

The privately-held company shipped 17.3 million smartphones in Q3 – a 211 per cent increase from Q3 2013. Its global market share more than doubled during that period, from 2.1 per cent to 5.6 per cent, according to IDC.

In its first move into wearables, Xiaomi launched a $13 fitness and sleep tracker in August. The Mi Band has a 30-day battery life and can also unlock a person’s smartphone when in close proximity — eliminating the hassle of entering a password.

Misfit says its Shine activity tracker is the best selling in China. App Annie said the top five connected device apps in the health and fitness subcategory in August were Fitbit, Up by Jawbone, Garmin Connect, Nike+ FuelBand and the Shine.

Misfit is based in California but has a data science team in Vietnam, Reuters said.