Why has IGUS S&P 500 fallen 7.5% – when S&P 500 only fallen 5.5%?

Hello! Eternal noob here.

Based in the UK, and I have IGUS stock (S&P 500 hedged to GBP).

Over the past 5 days, the stock has fallen 7.5%. Damn. But the S&P 500 itself has only fallen 5.66%.

I understand that there will be some discrepancies due to FX forwards, etc. but almost 2% is a huge difference.

Does anyone know why this may happen?