Here are some charts that seem to suggest that this very low volume spike to new highs may have been an exhaustion move in stocks concurrent with a bottom in the US dollar.
On the SPX futures we have an overnight gap up over the long term downtrend off the 2007 high on a holiday after a light volume run. Price was rejected after marginal new highs and the short term uptrend has been broken.
On NDX futures we see that price failed to achieve the upper return line of its intermediate term uptrend making marginal new highs before being rejected. The uptrend (previously violated) from the July low is being threatened as well.
The Dow futures rallied to new highs, piercing its intermediate term return line as well as the downtrend from the 2007 highs creating the kind of "throw over" that is typical of an important top.
The Russell 2000 and financial stocks are showing extreme underperformance and non-confirmation of the new highs.
The US dollar index is still arguably showing a bottoming process. Today's intraday reversal from new lows is not shown.
I would look for a higher volume down day very soon that ends near the lows for the day to indicate that a top is in place. A 2-4% up day for the dollar with a clean technical break of trend resistance should accompany this. If we don't see that kind of action in the next couple of days, then the equities rally and dollar decline are likely to continue.