Why Afterpay, Nickel Mines, Nitro, & St Barbara shares are sinking

The S&P/ASX 200 Index (ASX: XJO) has followed the lead of US markets and tumbled lower today. In afternoon trade, the benchmark index is down 0.7% to 7,377.9 points.

Four ASX shares that are falling more than most today are listed below. Here’s why…