All of the indices are threatening a break to new highs, but the first to do so may be the Nasdaq 100.  The last three days have shaped a small handle, defended by the breakout gap for support, and lurking very close to the breakout threshold at 4,118. Technicals are net bullish although it's underperforming relative to the Russell 2000, which may delay money flow into the index.

The caveat for the Nasdaq 100 is the action of resistance in the Semiconductor index. The former trendline turned resistance, in combination with the 50-day MA (and today's modest sell off), suggests bears may not yet be done. I also don't like the underperformance of this index relative to the Nasdaq 100 dating back to July; today's selling delaying what had looked like a bullish relative shift in favour of semiconductors (which would ultimately feed back into Nasdaq 100 strength).
 

The lead index (for bulls) is the Russell 2000. The brief stall at the 200-day MA looks to have passed, although a body of work is required before it can challenge summer highs. However, momentum is with bulls after posting an oversold extreme earlier this month.
 

Also doing well is the Dow. It posted a big gain, and is working on the former 'bull trap' / 'evening star' from September. It even banked an accumulation day.

For Friday, bulls have their choice of indices to work with: Russell 2000, Nasdaq 100 and Dow each have their merits.  If there is a weak start, then the Semiconductor Index is the index most likely to suffer most.