A basket of unprofitable tech companies tracked by UBS has jumped 21% since the end of July, compared with a 2.1% advance for its profitable tech counterpart and the Nasdaq 100 Index’s 5.9% advance. The run-up has sent the group, which includes lesser-known companies like SoundHound AI Inc. and Unity Software Inc., near its highest since late 2021, back when rock-bottom interest rates were fueling a bubble in speculative assets that popped the following year.