We have used XMM-Newton's Optical Monitor (OM) images to study the local environment of a sample of 27 Ultraluminous X-ray Sources (ULXs) in nearby galaxies. UVW1 fluxes were extracted from 100 pc regions centered on the ULX positions. We find that at least 4 ULXs (out of 10 published) have spectral types that are consistent with previous literature values. In addition the colors are similar to those of young stars. For the highest-luminosity ULXs, the UVW1 fluxes may have an important contribution from the accretion disk. We find that the majority of ULXs are associated with recent star-formation. Many of the ULXs in our sample are located inside young OB associations or starforming regions (SFRs). Based on their colors, we estimated ages and masses for star-forming regions located within 1 kpc from the ULXs in our sample. The resolution of the OM was insufficient to detect young dense super-clusters, but some of these star-forming regions are massive enough to contain such clusters. Only three ULXs have no associated SFRs younger than ∼50 Myr. The age and mass estimates for clusters were used to test runaway scenarios. The data are in general compatible with stellar-mass binaries accreting at super-Eddington rates and ejected by natal kicks. We also tested the hypothesis that ULXs are sub-Eddington accreting IMBHs ejected by three-body interactions, however this is not supported well by the data.
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