Investec reported on Thursday that domestic currency depreciation against the sterling forced a 25.6% slump in net profit.The South African financial services group posted results for the six months to 30 September, showing a net profit of £121.6m, compared with a figure of £163.4m a year earlier.On a lighter note, the company reported an increase in adjusted earnings per share from 3.7% to 19.7p. The firm's dividend also increased 6.3% during the period, to 8.5p per share.Chief executive Stephen Koseff said: "These results demonstrate that we are delivering on our promises. The results would have been even stronger but for the continued weakness of the Rand."As of 11:50 on Thursday, Investec's share price fell 1.09% to 587.50p per share.