Index Ventures’ Jahanvi Sardana shares the truth about TAM and what founders should focus on instead

Summary

Early-stage founders just can’t get away from TAM — the concept of having a total addressable market for their startup to disrupt and conquer. But Index Ventures partner Jahanvi Sardana has a reminder for all those founders worried about finding TAM for their product or service: many startups have emerged from markets that, at the time, were essentially nonexistent. “What was the market for search before Google?” Sardana asked the audience at TechCrunch’s 2025 All Stage event in Boston, held earlier this month. “What was the market for operating systems before Microsoft, or the market for cloud before Amazon?” Sardana compares TAM to surfing. Every few years, there are massive waves founders must ride — first came the internet, then the mobile wave, then the cloud, and now, she said, the biggest wave of all: artificial intelligence. “Have you shaped the right product to ride this wave?” she continued. “That’s what we call product market fit.” Which TAM bucket are you in? Sardana places TAM into three buckets: known market, emerging market, and invisible market. The first, known market, already exists, and it is when a founder seeks to replace a legacy incumbent and must prove to an investor why their startup idea is better. Techcrunch event San Francisco | October 27-29, 2025 “Everyone brushes their teeth,” she said. “You have to tell me why you’re building a better toothbrush.” The emerging market is when a certain sector of the market is using a product, and there is potential for it to go mainstream. “Think about non-alcoholic beer before it became cool,” Sardana said. Then there is the invisible market, which Sardana calls “the biggest trap,” and “also a little bit of a dark art.” The market doesn’t exist, and a founder has to essentially create the one and provide investors with evidence of how innovative they can be. “Think about smartphones in 2006, nobody knew they wanted them and they changed the world,” she said, later adding that “people don’t know what t...