A sharp rise in pre-tax profits in the half year to 30 November sent shares in Fiske higher, even as the stockbroker sounded a cautious note on 2011.Pre-tax profits jumped to £369,000 from £286,000 over the same period the previous year on revenues that rose to £2.23m from £2.04m.The rise in profits was due to increased private client commissions and the company keeping a lid on costs, said Fiske, which has maintained its 2p dividend.Fiske's caution on 2011 stems from its belief that major economic uncertainties in the world remain unresolved."In the eurozone there is the problem of potential sovereign defaults and the imperative need for governments throughout the EU to curtail expenditure and raise taxes," it said."In the USA the problems lie in the possibility of major defaults in the municipal bond market and the continued crisis in the housing market. At the same time the ability of the US Treasury and Federal Reserve to continue to create more money is being called into question."