Why Apple, Inc. is keeping the identity of many of its 23 recent acquisitions a secret

Speaking to shareholders at a meeting on Friday, Apple's chief executive Tim Cook noted that his company has acquired 23 companies over the last roughly 16 months.

That time frame would appear to exclude all of the known acquisitions reported to have occured within 2012, including Chomp, Redmaticia, AuthenTec and Particle.

For its fiscal year 2013 (the accounting year that ended last September), Apple reported $496 million in net "payments made in connection with business acquisitions." Companies that Apple was reported to have purchased during that period include WiFiSlam, Locationary, HopStop, Passif Semiconductor, Matcha, Embark and AlgoTrim.