The second profit warning in a year from Standard Chartered and some underwhelming results from Lloyds ensured that the banking sector was the worst-performing segment in London on Tuesday.Shares of Asia-focused StanChart were down 9% in afternoon trade after the bank warned that second-half underlying profits would be below last year's. In August, the company had guided to an improvement in profits in the last six months of the year.Third-quarter pre-tax profit dropped 16% to $1.53bn as a 1% increase in revenue was offset by higher impairments and costs.The stock, trading around the 999p level, had "dipped below the £10 mark for the first time in five years", noted IG's David Madden.Meanwhile, underlying profits were higher than expected at Lloyds Banking Group, rising 44% year-on-year in the third quarter to £2.16bn.However, shares fell 2.4% as analysts raised concerns about further PPI impairment charges and how Lloyds will fare amid the recent slowing of the UK housing market. The company also confirmed cost-cutting plans to slash 9,000 jobs and close a net 150 branches.Lloyds said it was in ongoing discussions with the Bank of England's Prudential Regulation Authority (PRA) regarding the resumption of dividend payments, but the payout is thought to be largely dependent on the PRA's forthcoming stress tests, the results of which are due on 16 December.Royal Bank of Scotland and Barclays were also trading in the red, down 0.5% and 0.1% respectively.Top performing sectors so far todayMobile Telecommunications 4,548.65 +2.25%Forestry & Paper 10,846.76 +2.03%Mining 15,276.05 +1.91%Industrial Transportation 2,860.67 +1.84%Health Care Equipment & Services 5,723.32 +1.62%Bottom performing sectors so far todayBanks 4,341.93 -1.07%Chemicals 9,556.31 -0.69%