 Welcome to the Voice of America's Newswords. The American company, Apple Inc., recently rose above $3 trillion in market value. Milestone The milestone made Apple the world's most valuable company for a brief time on the American Stock Index, the S&P 500. The demand for iPhones and computers helped Apple reach the milestone. In this example, a milestone is an important point in the progress of a business. It can also be a very important event or move forward, like a 10th or 100th birthday.