Apple surged into uncharted territory this week, and that has one technical analyst pressing the panic button.
On CNBC's "Trading Nation" Thursday, Rich Ross identified what he called the "single most important technical level in the world," and said it's giving him a reason to sell the tech giant.
The Evercore ISI technician pointed out that while the stock is in a "strong structural position" that allowed Apple to hit new highs, it hasn't broken out from a key technical level that would have him more bullish on the stock.
"You haven't taken out the old weekly closing high, and the weekly closing price is the most important price in technical analysis," said Ross. "That comes in at that $156 level."
From there, said Ross, Apple could potentially "establish a double top" heading into what has historically been the "worst month of the year" for the S&P 500 in the last 30 years. The technician believes that if Apple can't hold that $156 level, then it could potentially even drop down to the 50-week moving average, currently sitting around $133.
In other words, Apple could fall almost 15 percent from Thursday's levels.
Apple soared to an all-time high following the company's earnings beat on Tuesday. Its surge was the main driver for the Dow on Wednesday at the market's open, with the index crossing the 22,000 level.