Summary Box: IBM names first female CEO

NEW EXECUTIVE: IBM Corp. named the first female CEO in the company’s 100-year history. The selection of Virginia “Ginni” Rometty was announced Tuesday.

THE MILESTONE: It’s a statement about the growing influence of women in the top tiers of business.

THE CAVEAT: Although women have made momentous strides, breaking through corporate America’s “glass ceiling” over the past half century, a woman’s ascendance into the chief executive position of a major corporation still holds significance. Currently, only 16 Fortune 500 companies are led by a woman; Rometty and a new female CEO at Mylan Inc. would make that 18 when their appointments take effect on Jan. 1.