Shenton joined Artemis in 2012 on the back of a five-year spell at Polar, where he managed a UK equity long/short mandate. He was appointed co-manager on Adrian Frost's £5.5 billion Income fund in 2014.
Meanwhile Marsh, who was made a partner at Polar during his 12 years with the business, joined Artemis in February 2018 to work alongside Frost and Shenton on the Income fund.
Shenton has 15 years' experience, which includes a spell at F&C Asset Management, before joining Polar.
Meanwhile Marsh has 20 years' experience, which includes stints as head of equity sales at Investec Investment Bank and as an analyst for ING Charterhouse and then for Merrill Lynch.
Artemis senior partner Mark Murray said: ‘We have invited Nick and Andy to join Artemis’ partnership in recognition of their contribution to the income franchise in particular and to Artemis as a whole.
‘Our success rests on excellent long-term investment performance and client service. Our structure as a partnership brings stability and, we believe, helps us always to put our clients first.’
The Artemis Income fund returned 21.4% in the three years to the end of January against an average of 16.8% for the UK Equity Income sector, placing it 30/104 in its peer group.