Dropbox valuation buzz is as much about timing as dollars

Dropbox raised $756 million in its IPO, pricing shares at $21. That's above its already-increased offering range, and indications are that it will open trading today much higher.

But most of the attention so far is on a fully-diluted IPO valuation ($9.23 billion) that falls a little short of Dropbox's last private-market valuation.