You'd never know it, but Apple (NASDAQ:AAPL) has been on a buying spree lately. Of course, Apple doesn't announce its acquisitions unless it absolutely has to, such as when it acquired publicly traded fingerprint sensor specialist AuthenTec last year for $356 million. Avoiding disclosure is just another reason why the company prefers the small, specialized purchase to the big, flashy one.

CEO Tim Cook recently spoke at the D: All Things Digital conference, and dropped an interesting tidbit about the company's recent acquisition pace. Before this fiscal year, Apple would typically pick up a new company every 60 to 75 days, which would translate into roughly six purchases per year. Apple has already about nine companies this fiscal year, which started in October.

The only one of these that's been confirmed has been WifiSLAM, an indoor GPS start-up that uses Wi-Fi signals to pinpoint location. That pick up only reportedly cost $20 million, well below the disclosure radar.

Cook specifically said that Apple did not bid for Waze, the crowd-sourced traffic data aggregator that's been all the craze lately. Apple, Facebook, and Google have all been reportedly interested in buying Waze. That possible deal makes some sense for the social network or search giant, but the $1 billion that Waze is reportedly looking for puts it out of the Mac maker's sweet spot.

Investors can only speculate as to what other eight small companies Apple has acquired over the past eight months. It's likely that Apple is quietly buying companies to bolster its controversial Maps service. Cook noted that Apple believes mapping and location are extremely important going forward, which is why management is "investing as much as we are." He also acknowledged that Maps is still incomplete, noting that it's been greatly improved but that it's "not there yet." Those comments hint that Apple may be buying companies to improve Maps.

Services are also another key area where Apple lags the competition. Two rumored upcoming services are payments or online music streaming, so Apple could be scooping up smaller players in these realms to integrate into its inevitable offerings.

Even though Apple's been on a buying frenzy, those purchases haven't put a dent in its cash balance yet.

Fool contributor Evan Niu, CFA owns shares of Apple. The Motley Fool recommends Apple, Facebook, and Google. The Motley Fool owns shares of Apple, Facebook, and Google. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.