Signs of a bubble in the stock market haven't yet materialized, Bob Doll of Nuveen Asset Management said Monday.
"A bubble consists of ... overvaluation, overownership and overleverage, and I don't think we have any of those three in the equity market," he said. "The bubble talk's been going on now a couple of months, and the market's up eight weeks in a row, right in the face of those who've used the word 'bubble.' "
Stocks ended the day lower after posting an eight-week bull run.
(Read more: Stocks end lower after 8-week run higher)