Whether the current stock market follows the efficient market theory is a topic that has been studied all the time. We use Hurst exponent to test whether the price series and short interest series of GME and AMC affected in the WallStreetBet event have long-term memory. We hope to test whether there are price bubbles in the market and whether abnormal price fluctuations are related to short positions in this way. In the end, we found that even though the prices of GME and AMC rose sharply, their price sequences did not have long-term memory, but short interest sequences had long-term memory. This proves that market sentiment does not affect the price, on the contrary, the short squeeze caused by the excessive short position causes the excessively high price.