By Dan Weil The S&P; 500 index bounced back 6.5% last week, but it still has sunk 13% so far this year. Stocks showed signs of life last week, with the S&P 500 rising 6.5%. Several strong earnings reports and buoyant news on consumer spending made investors feel a bit more comfortable about stocks. But that doesn’t mean the market is out of the woods. The S&P 500 index has slid 13% so far this year. Morgan Stanley Chief Investment Officer Michael Wilson for one is skeptical that equities have escaped their downturn. “Last week’s strength will prove to be another bear market rally in the end,” …