S4 Capital: Revenue down and debt up at Sir Martin Sorrell’s ad giant Media Sir Martin Sorrell’s S4 Capital’s post-pandemic struggles have carried through into its latest results, which revealed a sharp decline in revenue and ballooning debt. The London-listed media holding group, which ad guru Sorrell founded after a sudden exit from WPP in 2018, saw its net revenue reduce by 15.6 per cent from £445.5m to £375.1m [...]