Venture capital firms (VCs) and underwriters form crucial connections that guide startups to public markets. This paper provides causal evidence supporting this claim and quantifies the value of these connections. Using plausibly exogenous variation from underwriter mergers and closures, we show that disrupting established VC-underwriter relationships impacts VCs' exit activity. After such relationship losses, VCs experience a 9.5% decrease in IPO exits and weaker fund performance. This suggests these horizontal relationships constitute valuable, relationship-specific organizational capital that generates value beyond the independent reputations of the intermediaries involved. Consistent with these relationships heavily relying on human capital, we find high post-merger employee turnover at underwriters strongly predicts relationship discontinuation. On average, only 23.4% of relevant personnel remain after mergers. Our findings demonstrate how specific intermediary networks shape capital formation and reveal important spillover effects of financial sector consolidation on entrepreneurial finance outcomes.