If you thought American Tower (AMT 1.46%) was done spending money after its recent shopping spree, think again.

On Friday, the wireless communication real estate specialist announced it has entered into an agreement to buy all of MIP Tower Holdings, a private real estate investment trust that also happens to be the parent company of Global Tower Partners.

When all is said and done, American Tower will pay for the deal using $3.3 billion in cash, and assuming roughly $1.5 billion of MIP Tower's debt, bringing the total purchase price to a whopping $4.8 billion. The transaction is expected to close sometime in the fourth quarter.

Like last time... only much, much bigger
For those of you keeping track, today's announcement arrived exactly four weeks after American Tower's last acquisition, in which it agreed to pay over $800 million for nearly 4,500 towers in Brazil and Mexico from Virginia-based NII Holdings (NASDAQ: NIHD).

And while American Tower leased those properties right back to NII Holdings and expects them to generate around $149 million in annual run rate revenue and $55 million in annual gross margin going forward, NII said it plans to use its new liquidity to invest in next-generation network deployments for its Nextel subsidiary in the two countries.

Of course, while today's acquisition is admittedly massive, it also shouldn't come as a big surprise considering just a few weeks ago, American Tower raised more than $1.2 billion through a new debt offering, which it said would be used in part to clean the slates of its existing massive revolving credit facilities -- this even though the company at the end of June had just told investors it still had around $2.6 billion in total liquidity remaining.

That's why I wrote at the time, "As a result of this housecleaning, I can't help but wonder whether American Tower has another big acquisition up its sleeve."

In retrospect, considering GTP's portfolio increases American Tower's U.S.-owned tower count by almost 25%, to call it "big" seems one heck of an understatement.

As it stands, GTP currently owns and operates around 5,400 domestic towers, 800 domestic property interests under third-party communications sites, has management rights to more than 9,000 domestic sites (most of which are rooftop assets), and owns 500 communications sites in Costa Rica.

What's more, around 63% of GTP's total revenue comes from sites on land that is either owned or on long-term leases with more than 20 years remaining.

With these assets now in American Tower's enormous hands, the company expects they'll generate around $345 million in revenue and around $270 million in gross margin in 2014.

Foolish takeaway
Finally, as American Tower's press release also points out, with all four major domestic wireless carriers currently undergoing "aggressive multi-year 4G LTE deployments," the GTP portfolio positions American Tower nicely to meet its goals of growing its adjusted funds from operations over the next five years -- a key driver of its ability to pay increasing dividends to shareholders given American Tower's relatively new status as a real estate investment trust. 

In the end, if you weren't convinced by American Tower's already-dominant industry position, I should think this news would do the trick. The market, for its part, apparently agrees and has driven shares of American Tower up more than 4% as of this writing.