Market risk is the risk that your product or service does not fit the needs or preferences of your target customers, or that the market size or growth is too small or too competitive for your startup to succeed. To reduce market risk, you need to validate your problem-solution fit, your product-market fit, and your go-to-market strategy. You need to conduct customer research, surveys, interviews, experiments, and tests to understand your customer segments, their pain points, their willingness to pay, and their feedback on your value proposition. You also need to analyze your market potential, trends, opportunities, and threats, and how you can differentiate yourself from your competitors.