Nat. Biotechnol. 32, 626–632 (2014); published online 8 July 2014; corrected after print 3 September 2014 and 25 June 2015

In the version of the article initially published, some companies that went public in 2013 were missing from the table of 2013 IPOs (Table 4). Thirteen companies have been added to the table, including Celyad (formerly Cardio3 Biosciences), Erytech, Immunicum, Innate Immune Therapeutics, Kadimastem, Karyopharm Therapeutics, Kindred, Macrogenics, Oncolys Biopharma, Reprocell, Tetralogic, Veracyte and Xencor; in the figure of global IPOs (Fig. 2), the number of IPOs in 2013 and the average dollar amount raised have been corrected to reflect the additional companies.