Cumulative distribution function of eccentricities. dMB15 and B16 adopted an eccentricity distribution p_e ∝ e^−0.4 (green) based on a sample of massive spectroscopic binaries (Sana et al. 2012) that are dominated by short-period systems P < 20 days and therefore weighted towards lower eccentricities 〈e〉 = 0.3. MD17 (and references therein) found that massive binaries with intermediate (blue) and long (red) orbital periods are weighted towards higher eccentricities 〈e〉 = 0.6 and are sufficiently modelled by a power-law distribution p_e ∝ e^0.8 with a turnover above e > 0.8.