Mróz et al. (2016) present the discovery of a high mass ratio system from a gravitational microlensing event. The planet to host star mass ratio of this system is 0.0117 ± 0.0004. However, the mass of the host star is not well constrained. If the host star has the same mass as the Sun, the planet's mass would be ~12.2 times the mass of Jupiter. With this mass, the planet would be just below the deuterium-burning limit, generally regarded as the boundary separating planets and brown dwarfs. If the host star has a lower mass, then the planet's mass would be smaller. Nevertheless, even if the host star has 0.18 times the mass of the Sun, the planet would still have roughly twice the mass of Jupiter. Having such a high planet to host star mass ratio makes this planetary system quite an extremely one. The planet is identified as OGLE-2016-BLG-0596Lb.
Reference:
Mróz et al. (2016), "OGLE-2016-BLG-0596Lb: High-Mass Planet From High-Magnification Pure-Survey Microlensing Event", arXiv:1607.04919 [astro-ph.EP]
