Ethereum has bounced from $2,220 to $2,550 over the past two weeks, marking a 15.3% increase as market speculation around U.S. Fed interest rates renewed investor interest in cryptocurrencies. However, several key factors may hinder Ethereum's ability to sustain a rally to $4,000.

The ETH/BTC pair recently fell to a 40-month low, indicating Ethereum's underperformance relative to Bitcoin, which has seen positive ETF flows. Additionally, ongoing sales from the Ethereum Foundation, including 300 ETH sold last Friday, contribute to bearish sentiment. The Foundation has sold a total of 3,466 ETH this year, which could signal caution about future price movements.

Moreover, the rising supply of ETH on exchanges has reached 21.46 million coins, increasing the risk of selling pressure. Currently trading at $2,555, Ethereum may face resistance at the $2,800 level. A breakout could lead to a $3,000 surge, while failure to breach this resistance could see prices retracing toward $2,000.