Twenty years after the introduction of the theory, we revisit what it does—and doesn’t—explain. by Clayton M. Christensen, Michael E. Raynor and Rory McDonald Please enjoy this HBR Classic. Clayton M.

Adam Hayes, Ph.D., CFA, is a financial writer with 15+ years Wall Street experience as a derivatives trader. Besides his extensive derivative trading expertise, Adam is an expert in economics and ...

Apple's autocorrect on iPhone and iPad always aims to help when you're typing a message, but it's by no means perfect, and some of the replacements it continually spews out can be frustrating.