Sprint Nextel Corp., the nation’s third-largest wireless carrier, said Wednesday that it had it swung to a first-quarter loss as investments in operations wiped out modest gains in sales.

For the January-March quarter, the Reston, Va.-based company reported losing $211 million, or 7 cents per share, versus earnings of $417 million, or 14 cents per share, a year ago.

Excluding one-time amortization charges, Sprint Nextel – which has operational headquarters in Overland Park – said it earned 18 cents per share, missing the 22 cents per share expected by analysts polled by Thomson Financial.

Revenues for the quarter were $10.1 billion, up from $10.07 billion a year ago. Analysts had expected $10.31 billion in sales.

The company reiterated its expectation of annual revenues between $41 billion and $42 billion.