Fintech startup Mercury has raised $300 million in a Series C funding round led by Sequoia, boosting its valuation to $3.5 billion. This marks a significant increase from its previous $1.62 billion valuation after a Series B round in 2021. The funding will support Mercury's continued growth, which includes reaching $500 million in revenue and achieving 10 consecutive quarters of profitability. The company now serves over 200,000 customers, boasting a 40% year-over-year growth rate. Mercury plans to explore acquisitions with the new capital.