Until 1 February Petharam and Gunn co-managed the fund alongside Anthony Nutt and John Hamilton, who will continue to be involved as deputy managers.
Jupiter said there will be no change to the fund’s investment process as a result of the promotions now in effect.
Petheram has worked alongside Hamilton since 2006 when he joined Jupiter’s fixed interest team. He previously worked at Moody’s Investor Services and has experience as a credit analyst across a number of sectors.
Gunn joined Jupiter’s UK equities desk in 2007 and has worked with Nutt, who is head of UK equities at the firm, since then. He has more than 20 years’ experience as a sell-side investment analyst and formerly worked at Arbuthnot Securities and Bear Stearns International.
Hamilton will continue to lead manage the Jupiter Corporate Bond Fund, while Nutt will remain lead manager on the Jupiter Income Trust, Jupiter High Income Fund and Jupiter Dividend and Growth Trust.
The Jupiter Distribution Fund has also recently moved to the IMA Mixed Investment 0-35% Shares Sector (formerly the Cautious Balanced Sector), following the sector’s renaming.
Since July 2010, when Petheram and Gunn joined the fund as co-managers it has returned 12.24%, compared to a sector average of 9.12%, and is ranked third out of 11 funds in the sector, according to FE (as at 30 January).
John Chatfield-Roberts, chief investment officer at Jupiter, said: "This is a sensible extension for Rhys and Alastair who have proven their abilities since becoming co-managers of the fund in 2010. These well-deserved promotions outline once again our commitment to growing our team of talented fund managers."
The aim of the Jupiter Distribution Fund is to provide a sustainable level of income and the prospect of capital growth.