Deven Sharma, incumbent in the role at the bank, is set to leave the position in the near future and Mr Peterson is scheduled to take up the reins in his new job on 12 September.
It is thought by many experts in the sector that this decision has been based largely on the fact that Mr Sharma is widely believed to have made a large error when deciding to use S&P's system to downgrade the US's credit rating from AAA for the first time in history recently.
In a statement released by S&P - which has a presence in 23 countries across the world - it was noted that Mr Sharma will "pursue other opportunities" following his departure.
Noel Herbert, credit strategist at Mitsubishi UFJ Securities, told Bloomberg: "It looks like heâs being helped out the door."
By Asim Shah