In poker, a “tell” is an unintentional or unconscious action that may (or may not) indicate an underlying intention… for example, a poker player may betray himself by (say) scratching his nose when he’s holding a great hand.

In markets, a “tell” is something that – usually in hindsight – signifies a turning point. We might be approaching a “tell” for tech stocks, which have seen a huge bull market in recent years. As shown below, since the global economic crisis, two of the most tech-heavy indices in the world – NASDAQ in the U.S. and the Shenzhen stock market in China – have performed far better than the rest of the world.

Since its lows in 2008-2009, the NASDAQ is up 283 percent and the Shenzhen has gained 310 percent. In the meantime, the S&P 500 is up 207 percent. Both have outperformed the S&P 500 and the ...