I am curious, does anyone know what caused the massive drop in value yesterday and the day before?
I would think that (even though it is a very volatile market) it is strange CombiCoin fell from 17.20 USD to 13.57 USD in just 24 hours. Because it is backed by the top 30, did all the backing coins drop so dramatically?
Luckily it is already recovering fast!

Yes, the drop in CombiCoin is mainly based on the price decline of its underlying assets. Bitcoin plunged by more than 20 percent, and smaller cryptocurrencies, which are part of the portfolio, fell even more. NEO or IOTA for example lost about 25 percent resp approx 30 percent.
Regards