To measure success metrics of Facebook/Instagram Story, there are several key metrics that product managers can focus on: 1. Completion Rate: This metric measures the percentage of viewers who watched the entire story from beginning to end. This metric is a good indicator of how engaging and interesting the content is. 2. Reach: This metric measures how many unique viewers saw the story. A high reach means the story is being seen by a large number of people and is gaining traction. 3. View Time: This metric measures how long viewers are watching the story. A longer view time indicates that the content is engaging and holding the viewer's attention. 4. Conversion Rate: This metric measures the percentage of viewers who took the desired action, such as clicking a link or purchasing a product. This metric is important for measuring the effectiveness of calls-to-action within the story. 5. Engagement Rate: This metric measures the number of interactions with the story, such as likes, comments, and shares. A high engagement rate indicates that the content is resonating with the audience and is shareable. By monitoring these metrics, product managers can gain insights into how well Facebook/Instagram Story is performing and make data-driven decisions to improve the product.