To the continuous outrage of the nation's financial sector, Salmon Chase, Lincoln's Secretary of the Treasury, granted to Jay Cooke & Co. the exclusive right to sell all Treasury paper during Chase's tenure. Cooke was given "points" (a percentage) of every sale made.
From the book Jay Cooke: Financier of the Civil War Volume I by Ellis Paxson Oberholtzer:
Banking services. P. 210: On 2/7/62, Chase asks Cooke for a personal loan of $2,000 for "a store I am rebuilding" in Cincinnati.
Wealth management. Throughout 1862, Jay Cooke was investing Chase's personal funds for him and advising him on finances. In a couple of letters (at least), Chase admonishes him for mixing personal business into official communications, since his official correspondence had to be archived. They met privately on a continuous basis about Chase's finances.
Free stock and a plush job. P. 188: Chase "again had a vision of resigning from the Treasury Department to take [the] presidency" of the Washington and Georgetown Street Railroad Company, a Cooke & Co. concern, in which Chase was given free stock. On 5/31/62, he dropped the hint in a letter ("I was strongly inclined..."). He was needed where he was, however, and Cooke did not act on Chase's employment hints.
We should be mindful that the Gilded Age started with Lincoln.