To track the wild swings in investor attitudes towards AI stocks, there’s no better barometer than South Korea’s Kospi index. Right now it’s sending the message that the market is back in full-on greed mode. The benchmark has soared 22% in the past 10 sessions, putting it back in a bull market.

The Kospi trades like a pure play on AI because two big winners from the data center boom — Samsung and SK Hynix — account for half the index. A pair of earnings reports late last month from big AI spenders Microsoft and Amazon eased concern about a bubble.