Have a feeling the SPX is building up for a blow-off top. Incredible momentum in the index at the moment.
2940 seems the logical short term target on the back of last night's breakout (3.8% upside).
3100 seems to be the stretch target sometime in February imo (9.4% upside).
The last legs of a strong run like this are generally the quickest. From the top I don't think the market will necessarily plummet right away. Some form of a wide topping pattern is more likely; there is a lot of bullish inertia in the market at the moment. Bar a crash circa 1987, that form of inertia doesn't turn on a dime.