Looking for signs of exuberance that typically signal a market top? How about mom and pop backing up the SUV at the local brokerage.

Clients at TD Ameritrade added to stock holdings for a 10th straight month in November, driving a gauge of retail investor sentiment 15 percent higher to a record, according to the online brokerage’s website. That was the “largest single-month increase ever” in the firm’s IMX measure, as investors piled into an equity market that’s on pace for its best year since 2013.

“The retail investor has become a bit more of a believer,” Joe “JJ” Kinahan, chief market strategist at TD Ameritrade, said in an interview at Bloomberg’s New York headquarters. “We don’t want people to get overzealous, if you will. This is controlled exuberance.”

There are other signs retail investors have growing faith that the market will extend the eight-year bull market. According to Conference Board data, the net percentage of Americans who expect equities to rise…