Craig Johnson, Chief Market Technician at Piper Sandler, used his CNBC Morning Call Sheet appearance to flag concerns for self-directed investors riding the AI trade. Introducing Piper Sandler’s report The Bull Market That Few Trust, Johnson said: “The technology sector is now 41% of the investable assets here in the US. Semiconductors are 50% of ... Wall Street’s Top Chartist Warns US Tech Stocks Now At Highest Concentration Since the 2000 Bubble