Express Scripts CEO says estimates are "aggressive," shares drop

Nov 6 (Reuters) - Express Scripts Holding Co Chief Executive George Paz said on Tuesday that Wall Street's outlook for the pharmacy benefits manger's financial results in 2013 may be too rosy given what he has heard from clients concerned about the economy.

``I'm not saying this is all a doom and gloom story. I'm just telling you based on what we hear ... we think that the numbers out there are really aggressive,'' Paz told a crowd of investors and analysts on a conference call.

Shares dropped about 15 percent to $53.44 in busy early trading on Nasdaq.

(Reporting By Caroline Humer; Editing by Gerald E. McCormick)