The move is part of an expansion of Fidelity's North American investment capabilities following the resignation of Vatis, and is one of several changes that will see it double its team to four US portfolio managers.
Vatis, who has run the fund since February 2007, is leaving on 21 December and Adrian Brass will become interim manager on the fund until Kaye joins in the first quarter of 2013.
Brass will continue to run the Fidelity Funds America fund, but will hand the reins of the Fidelity American Special Situations fund to Angel Agudo, allowing Brass to launch a new equity fund in the first half of 2013. Meanwhile Aditya Khowala will take on the Fidelity Funds - American Growth fund currently managed by Vatis.
Fidelity said that Agudo and Khowala had eight and seven years respectively of experience in Fidelity's investment team, and had been preparing to take on new portfolios in the US equity team for the past year, after running in house pilot funds.
Kaye has been a US equity fund manager for 16 years, most recently at DSP, and joined the boutique from Henderson Global Investors where he had been head of North American Equities.
Fidelity Worldwide Investment Global CIO for Equities Dominic Rossi, (pictured) said: 'The combination of Peter and Adrian Brass, along with the transfer into the team of two of our most promising new portfolio managers creates many new opportunities for us to expand the breadth and depth of our fund range. These appointments, combined with the significant concurrent expansion of our in-house research capabilities, create one of the strongest and best-resourced US equity teams outside North America.