Why is the Northern Star (ASX:NST) share price sinking 3% today?

Unfortunately, the S&P/ASX 200 Index (ASX: XJO) has not kicked off the trading week on a good note so far this Monday. At the time of writing, the ASX 200 is down by 0.43% at 7,364 points. But the news is a little worse for the Northern Star Resources…