It certainly looked like a breakout, at least for today, but it would have been more convincing if the volumes had not remained thin. As such it looked like a short squeeze engineered by the wiseguys ahead of the FOMC meeting.
SP 500
NDX
"Let us then compose ourselves, and bear a firm and courageous heart. Let us feel what we really are,—sinners attempting great things, and succeeding at best only so far as to show that we do attempt them. Let us simply obey God's will, whatever may befall; whether it tend to elate us or to depress us, what is that to us? He can turn all things to our eternal good. He can bless and sanctify even our infirmities." J. H. Newman