Wall Street reversed lower in sharply higher volume Tuesday as Congress returned from an election recess to start talks on averting the fiscal cliff. The S&P 500 fell 0.4%, while the Dow Jones industrial average dipped 0.5% after both rose as much as 0.7% earlier. The Nasdaq fell 0.7% after rising 0.5% intraday. Volume soared 136% on the NYSE and rose 30% on the Nasdaq compared with Monday's levels. Cisco Systems (CSCO) jumped in after-hours