Shares of American Tower (NYSE: AMT) hit a 52-week high today. Let's look at how it got here and see whether clear skies are ahead.

How it got here
As the market for wireless services has expanded, so has the need for tower space. That's been a boon for American Tower, which rents tower space to wireless providers around the world.

The stock's rise has been driven by the company's continually improving performance financially. In the first quarter of 2012, revenue rose 23.8% to $696.5 million and cash flow from operations jumped 41.6% to $402.0 million.

Its stock has had a great run since 2009, closely matched by infrastructure provider Crown Castle International (NYSE: CCI). Both companies are aggressively expanding internationally to capture the growing market outside the United States. In fact, these have been better stocks for investors in the past five years than their customers AT&T (NYSE: T) and Verizon (NYSE: VZ).

AMT Chart

AMT data by YCharts

Let's take a look at the some of the group's current valuation, capital efficiency, and balance-sheet metrics.

Company

Price/Book

Return on Assets

Total Debt

Forward P/E
American Tower 7.8 5.6% $7.3 Billion 34.0
Crown Castle International 6.2 4.2% $8.4 Billion 55.7
AT&T 2.0 3.9% $65.7 Billion 13.9
Verizon 3.4 5.4% $51.6 Billion 15.7

Source: Yahoo! Finance.

The company recently converted to a REIT, which will mean regular distributions to shareholders, although it's a relatively modest 1.2% right now. If cash flow continues to improve, the payout will go up as well.

What's next?
Can the rally continue? I have my doubts. A 34 forward P/E ratio is expensive, and American Tower will have to continue to grow rapidly just to live up to expectations. One slip-up and the stock could take a nasty fall. I like to have upside risk in my investments instead of buying perfection and risking the downside.

The CAPS community, however, has a different opinion. The stock has a four-star rating, and 152 out of 167 All-Stars think the stock will outperform the market as it continues to capitalize on the revolutionary growth in mobile.

American Tower's growth and stock performance have been impressive, but I don't think it can fly much higher. The company can't squeeze too much out of customers because they could just build their own towers, and with the stock priced the way it is, I don't see much value.

Interested in reading more about American Tower? Add it to My Watchlist, and My Watchlist will find all of our Foolish analysis on this stock.