Why Karoon Energy, Mesoblast, Mineral Resources, and Sigma shares are falling today

In afternoon trade, the S&P/ASX 200 Index (ASX: XJO) is back on form and on course to record a decent gain. At the time of writing, the benchmark index is up 0.5% to 8,215.4 points.

Four ASX shares that have failed to follow the market higher today are listed below….