Larry Merlo certainly has a tough act to follow.

Larry Merlo certainly has a tough act to follow.

As Tom Ryan’s successor as chief executive officer of CVS Caremark, Merlo’s work will be measured against that of one of the legendary figures in mass market retailing.

During his 17 years at the company’s helm Ryan directed the expansion of CVS from a, $3.95 billion, 1,284-store regional drug chain into a $96.4 billion operation with some 7,200 drug stores from coast to coast and a leading presence in the pharmacy benefits management business. Motivated by a desire to make health care more accessible, affordable and effective, his visionary approach, which also included expansion into the in-store clinic field, spurred CVS to attain the scale and develop a range of capabilities rivaled among pharmacy operators only by Walgreens. Ryan’s achievement will leave a lasting mark on the company he headed, the industry of which it is a part and, quite possibly, the nation’s health care system.

While Ryan was certainly the catalyst for the transformation of CVS, he didn’t reshape the retailer alone. One of the most talented groups of executives in the industry, which from the start of the Ryan era included Larry Merlo, played a pivotal part in the process.

Merlo joined the company in 1990 when the retailer he worked for, Peoples Drug, was sold to CVS, a move that inaugurated a period of rapid expansion through acquisition. He subsequently proved invaluable in overseeing the assimilation of the chains added to the CVS retail empire, a group that included Revco, Eckerd, Osco/Sav-on and Longs. At the same time, he helped make CVS/pharmacy one of the most innovative, dynamic and successful retailers in America, a characterization that applies to the front end as well as the pharmacy department.

Now Merlo takes on his most difficult assignment — building on the formidable legacy of Tom Ryan.

"We are focused on delivering on the promise of our integrated pharmacy health care model," Merlo said when he assumed the chief executive’s post at the beginning of March.

Typical of his approach to business, the clarity with which Merlo sees the challenge ahead — both for him personally and for the company he heads — offers reason to believe that he will find the means to master it.