Why a2 Milk, American Pacific Borate, Appen, & Incitec Pivot are tumbling lower

The S&P/ASX 200 Index (ASX: XJO) is on course to start the week with a strong gain. At the time of writing, the benchmark index is up 0.95% to 7,148.8 points.

Four ASX shares that have failed to follow the market higher today are listed below. Here’s why they are tumbling lower:

The A2…