Tech bulls may not have to wait much longer for fresh highs, if the single-biggest trade in the Invesco QQQ Trust ETF on Thursday is any indication.The trader spent $24 million on a three-part call spread that needs the Nasdaq-100 index to make an all-time high by the end of this month, a high-conviction directional bet and the third-biggest trade among all options exchanged on Thursday.Despite recent volatility, the Nasdaq 100 has been effectively flat since May 14.