Billionaire Ken Griffin just bought two of the most significant documents ever signed by President Abraham Lincoln, adding to his trove of Americana. 

Griffin reset the record for any document signed by Lincoln when he paid Sotheby’s $13.7 million on Thursday for a rare, handwritten copy of the 13th Amendment. The president signed the single sheet of vellum in 1865 ending slavery nationwide, and it is one of only four surviving copies to remain in private hands.