Apple shares have crushed the market’s performance so far this year. But investors should not expect easy gains going forward, according to the newest Wall Street analyst on the stock.

Wells Fargo’s Aaron Rakers began coverage on Apple shares with a market perform rating, saying the smart phone maker’s immediate prospects are more uncertain after its recent iPhone product launches. Rakers joined the firm last month as its new IT hardware and networking equipment analyst.

The company’s iPhone 8 and iPhone X were released on Sept. 22 and Nov. 3 respectively.

“We believe strength in shares of Apple have, in part, been driven by a ‘chase-the-performance’ trade ahead of the iPhone 8/X product cycle,” wrote Rakers, whose LinkedIn profile shows he previously worked at Stifel Nicolaus, in the Tuesday note. “We think the shares could now see increased volatility, with a focus on incremental derivative demand and mix data points over the coming months.”

Apple shares fell 1.2 percent in early trading Wednesday after the report. Its shares are up 48 percent year to date through Tuesday versus the S&P 500’s 15 percent gain.

The analyst noted the risk of higher memory chip prices, which are essential components for the company’s computing and smartphone products.

“Given the tight memory supply/demand dynamics, Apple’s results could be negatively affected by lack of supply or higher-than-expected prices,” he wrote.

Rakers started his price target for Apple shares at $195, representing 14 percent upside from Tuesday’s close.

“While we applaud Apple’s execution and continual ecosystem buildout, the inevitable shift to what’s next should once again surface post the iPhone 8/X cycle,” he wrote. “We expect some investors to continually question Apple’s rate of innovation (focus on Apple’s significant R&D investments) for the iPhone as competitors offer similar features and cheaper smartphones.”

Apple did not immediately respond to a request for comment.