Clearwire Corp., the unprofitable wireless-broadband provider, tumbled after Google Inc., its third-largest shareholder, said it plans to sell its stake in the company.

Clearwire fell 5.5 percent to $2.14 at 9:33 a.m. New York time. Google, based in Mountain View, California, plans to begin sales as of Feb. 27 at $1.60 a share, according to a regulatory filing today. Clearwire has lost 54 percent in the 12 months through yesterday.

The Bellevue, Washington-based company, which is trying to build out a higher-speed long-term evolution, or LTE, network, said in a Feb. 16 regulatory filing that it may need to seek new capital to fund operations beyond the next year as losses widened in the fourth quarter.

Google held 6.5 percent of Clearwire, or 29.4 million shares, as of Dec. 16, according to data compiled by Bloomberg.

Clearwire reported a loss of 81 cents a share in the fourth quarter, from a loss of 79 cents a year earlier. In December, the company had said it was raising $595 million through two sales of common stock to build its LTE network.