Costco shares are down slightly in premarket trading after disappointing same store sales numbers. ... [+] (Photo by Joe Raedle/Getty Images)Getty ImagesKey Takeaways S&P 500 Hits Its 42nd High, Signaling Broad Market Strength With 80% Stocks Above Moving Averages China's Stimulus Boosts Stocks, But Concerns Linger About Long-Term Effectiveness Of Government Intervention PCE Data Suggests Controlled Inflation, Possibly Giving The Fed Room For Future Interest Rate CutsStocks closed higher on Thursday as the ...