Do Index Ventures and Y Combinator invest together?

Yes — Index Ventures and Y Combinator appear together in 22 tracked portfolio companies, including Castle, Codecademy, Cradle, Curtsy, Deepnote.

How do Index Ventures and Y Combinator compare on check size?

Index Ventures typically writes checks of $540K – $10.8M, while Y Combinator writes $500K.

Two firms that co-invest: side by side on stage, sector, check size, and track record, from public filings and the firms' own sites.

	Index Ventures	Y Combinator
Type	Venture capital	Accelerator
HQ	San Francisco	San Francisco
Founded	1996	2005
Check size	$540K – $10.8M	$500K
Stages	Seed, Series A, Series B, Series C, Growth, Late Stage	Pre-Seed, Seed, Series A
Sectors	AI & Machine Learning, Cloud Computing, Construction Tech, Cybersecurity, Developer Tools, Fintech, PropTech, SaaS, Sector Agnostic	AI & Machine Learning, Biotech, Climate Tech, Deep Tech, EdTech, Robotics, SaaS, Sector Agnostic, Space Tech
AUM	$16.2B	—
Tracked investments	371	6,130
Exits (acquired/public)	21	839
Led rounds on record	44	21
Dated deals, last 24 mo	27	1304

Do Index Ventures and Y Combinator invest together?: Yes — Index Ventures and Y Combinator appear together in 22 tracked portfolio companies, including Castle, Codecademy, Cradle, Curtsy, Deepnote.
How do Index Ventures and Y Combinator compare on check size?: Index Ventures typically writes checks of $540K – $10.8M, while Y Combinator writes $500K.