Thomson Reuters
In it, he explained his long thesis for pharmaceutical giant, Bayer.
Last year Bayer spun off its chemicals company, Covestro, and then in September announced a deal to take over seed-maker Monsanto.
That deal is pending approval from a dizzying number of regulators around the world.
Now, here's the crux of why Einhorn likes Bayer in all of this:
"Whether they make it to the altar, or get thwarted along the way, there's going to be a celebration for Bayer shareholders either way. With cake. And we like cake," he said.
Scroll down to get his full take on why.