Uber just added Postmates to its portfolio.

The ride-hailing company agreed to buy the food-delivery service on Monday for $2.65 billion in an all-stock deal. The news added to Uber shares' recent gains, rallying 6% on top of a 25% surge in the past three months.

Danielle Shay, director of options at Simpler Trading, said Uber is not on her buy list.

"Uber is one of the IPOs in the market that we've seen that has been a laggard for the majority of the year," Shay told CNBC's "Trading Nation" on Monday.

While Uber rallied in the second quarter, it has trailed the rest of the IPO stocks, names that have been public for less than two years. Uber is up 9% this year, while the IPO Renaissance ETF has surged 35%.

"The acquisition of Postmates is number one, expensive. Number two, the market share that Postmates has is incredibly small especially compared to DoorDash, and I think when you're looking at this and thinking is this going to be the straw that gets Uber out of this hole? I don't think so," said Shay. "Uber is a short on this news. I think you can short it around $35 and if it trades up to $40 I think I would short it there as well."

Uber closed Monday's session at $32.52 a share.

Ari Wald, head of technical analysis at Oppenheimer, is not as bearish on the stock. He sees continued momentum behind IPO stocks, including Uber.

"We do think it should be provided a tailwind with the strength IPOs in general. It's an 8% weighting in the Renaissance IPO ETF — that IPO ETF rates positively in our momentum work. We think it continues to lead," Wald said during the same segment.

Wald added that the hot IPO market may not be as frothy as some fear.

"Take this for instance, that IPO index is up 25% over the last 12 months, but for comparison purposes, it was up over 300% into the year 2000 peak. A real far cry from that, a much steadier ascent, strong but not too strong, we think it continues," said Wald, basing the historical comparison on a composite of the IPO ETF and Bloomberg's IPO index.