The investment firm's Jason Kupferberg sees the stock as underperforming the broader market.
Affirm shares at last check were 2.2% higher at $62.14.
The company went public in January at $49 a share.
That IPO price was higher than the targeted range, and the payment-technology company raised $1.2 billion.
Affirm had earlier boosted the target range to $38 from an estimated $33. Affirm sold 24.6 million common shares in the offering.
At the IPO price, Affirm was valued at $11.9 billion based on the shares outstanding listed in its regulatory filings, according to Bloomberg.
The company’s fully diluted valuation, including options and restricted stock units, was about $15 billion.
“Legacy payment options, archaic systems, and traditional risk and credit underwriting models can be harmful, deceptive, and restrictive to both consumers and merchants," the company said in its IPO prospectus.
"They are not well-suited for increasingly digital and mobile-first commerce, and are built on legacy infrastructure that does not support the innovation required for modern commerce to evolve and flourish.”