The rise in Rivian's stock price is attributed to broader market optimism driven by expectations of a strong earnings season and potential Federal Reserve rate cuts. The political shift with President Biden stepping down and the rising odds of a Trump victory, known for his pro-business stance, also contribute to the positive sentiment. Lower interest rates could reduce borrowing costs for Rivian, which is heavily investing in R&D and scaling up production, potentially boosting investor confidence in its future profitability.