Square has surged 167 percent this year alone, but Fort Pitt Capital senior equity analyst Kim Forrest says it could be time to pump the brakes on the payment stock.
"We don't own it, and this looks like a very dangerous momentum stock," she said Tuesday on CNBC's "Power Lunch." "Momentum people love growth, and it looks like it may be topping out here right now, especially with respect to the real transaction revenue."
"It's a cautionary tale," she added. "It's been great, but if I owned it I would certainly sell some of it now just to take some money off the table."
Square, whose CEO is Twitter chief Jack Dorsey, has been part of the high-flying payments space, which has also seen credit card stocks like American Express and Visa soaring to new all-time highs. But Mike Binger, portfolio manager at Gradient Investments, also believes other names in the group might actually be a better buy.
According to Binger, Square has become too expensive, and a possible change to its business model could also impact the stock.
"Don't forget that Square has applied for a banking license," he said. "If they get that license, they want to be a lender, and that's a whole different game that comes with a whole different multiple."
"I think Square is a stock priced to perfection, and I would wait for a better entry point on it," he added.
On Tuesday, Square was still trading around its all-time highs at $36.