(This story is for CNBC Pro subscribers only). The first Wall Street firm to initiate coverage on Snowflake after the cloud company's big IPO pop slapped a sell rating on the stock and warned of a "violent sell-off." Shares of Snowflake more than doubled in their first day of trading Wednesday and continued to swing in the following days . Summit Insights Group said in a note to clients that Snowflake is not a unique company in the enterprise software space, and the firm expects a pullback of more than 25% for the stock. "Our SELL rating is based on the belief that SNOW is the most expensive name in all tech, with limited differentiation with respect to Redshift, Big Query, and Azure SQL Database," the note said. Summit praised the company itself, calling it "cutting edge," but said Snowflake would need to execute "flawlessly" in the quarters ahead to justify its current price. The firm set a price target of $175 per share, which is 27% below where trading closed on Friday but still well above Snowflake's IPO price. Summit is a relatively small Wall Street shop, and bigger firms are likely to start their coverage of Snowflake after a post-IPO grace period. The firm also identified potential headwinds for the stock price in the months ahead, saying that insider selling and a potential secondary offering to raise more cash would create selling pressure. "SNOW's initial lockup expiration is on December 15th, during which 11.3 million shares are eligible for sale. With secondary offering likely, we believe the risks are elevated for investors," the note said. Snowflake, led by veteran CEO Frank Slootman , had high profile backers and customers, including Salesforce and Warren Buffett's Berkshire Hathaway . Snowflake shares fell 4.6% on Monday..