Shipments of wearables shot up nearly 200 percent in the most recent quarter. While that’s great news for the industry as a whole, data from research firm IDC paints a vivid picture of volatility among market share leaders.

Fitbit shipped 4.7 million wearables in the third quarter of this year, up from just 2.3 million during the same period a year ago. Despite doubling its shipments, the company’s market share fell more than 10 percent to 22.2 percent.

Apple moved 3.9 million devices in the three-month period, capturing 18.6 percent of the market in the process and narrowly edging out China’s Xiaomi which shipped 3.7 million wearables and grabbed 17.4 of the market. A year ago, Xiaomi shipped just 400,000 devices and held only 5.7 percent of the market. Because the Apple Watch debuted this past April, there’s no data from last year to compare it to.

IDC’s Ramon Llamas said the early stages of the wearables market have led to tight competition among the leading manufacturers and that Chinese vendors have seized upon market momentum to grab market share. Llamas added that China has quickly emerged as the fastest-growing wearables market, attracting companies that are eager to compete on price and feature sets.

True enough, Xiaomi has shown the most growth and potential as more than 97 percent of its volume has shipped in China, leaving plenty of room to expand to other regions.

Apple Watch image courtesy Jarrard Cole, WSJ