Wireless transmission towers aren't much to look at. The same goes for wireless transmission tower company stocks like American Tower (NYSE:AMT).

Shares of American Tower have made big gains over the last year, outpacing the S&P 500 and jumping from $5.80 to around $13. The market appears to think that the worst is over for the firm and that it's positioned to gain from improving demand for wireless tower space.

But judging from the company's quarterly financials dating back to its public listing in 1995, it's hard to imagine that the company will ever make money. Losses have been piling up at American Tower for nine straight years.

In its fourth quarter, the company reported revenue of just more than $191 million. But after American Tower paid its operating expenses, there was only $12 million left. A 6.2% operating margin isn't bad, but the trouble is, the nearly $3.3 billon of long-term debt on American Tower's balance sheet generated close to $68 million of interest last quarter, wiping out any hope of turning a profit.

And what about the costs of keeping its towers up to snuff? Last year, the company wrote off about $133 million in depreciation, but spent just $49 million on capital maintenance. At that rate of repair, the towers won't be standing long.

To put it bluntly, building and maintaining wireless transmission towers costs a lot more than what the company gets back from leasing them out to carriers.

American Tower did produce some free cash flow for 2003, though, which is a positive development compared with 2002. However, the firm trades at a fairly lofty enterprise value-to-free cash flow multiple of 34.

Wireless carrier consolidation doesn't help matters either. With AT&T Wireless (NYSE:AWE) now scooped up by Cingular (a joint venture between SBC Communications (NYSE:SBC) and BellSouth (NYSE:BLS)), there is one less major company leasing space on towers that transmit signals. Cingular plans to decommission as many as 4,000 overlapping cell sites. That could put price pressure on American Tower.

Wireless subscriber growth doesn't seem to be slowing down, which certainly works in American Tower's favor, as well as for other tower companies like Crown Castle (NASDAQ:CCI). But at its current height, American Tower's share price doesn't provide much of a view.

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Fool contributor Ben McClure hails from the Great White North. Ben doesn't own any shares mentioned here.