The positive reaction in Enovix Corp's stock price is directly tied to the announcement of achieving new milestones at its Fab2 manufacturing facility, including the completion of Factory Acceptance Testing for its Gen2 Agility Line. This development is critical as it keeps the company on track for initial sample production in Q2, a key factor for investors. The anticipation of the company's unique battery technology, which promises higher energy density through the use of a 100% active silicon anode, adds to the positive sentiment. Furthermore, the upcoming Q1 financial results announcement, despite the expected earnings loss, is likely factored into the current stock price movement as investors focus on the company's future growth potential.