Private Equity and Venture Capital (PE/VC) funds invest primarily in small and medium private companies. Their partnership with these firms shows great activism, often with implementation of good governance practices and value creation in processes, aiming to provide fast growth and make disinvestment with high profitability. The objective of this study is to investigate the relationship between PE/VC investment in private firms and the long-term performance of these companies shares after the IPO. Companies were divided by industry and two analyzes were performed: buy and hold and cumulative abnormal return (CAR). The first analysis shows mixed results in each industry. The group of PE/VC-backed firms performed better only in the sectors of Consumption, Real Estate, Healthcare and Utilities. The second analysis involved a comparison of companies returns with industry benchmarks and the regressions performed showed that PE/VC investment has a positive significant relation with CAR six months after the IPO. No significant evidence of this relation was found when these funds held their position or part of that in the corporate structure of the companies.