I noticed on icbit.se that future bitcoin prices for 4 months contract are about 50% higher than spotprices. Anybody has a plain explaination for this?
The "market" (at least icbit.se participants) believe Bitcoins will be worth 50% more than spot in 4 months.
If Bitcoins are worth $300 today and you believe in 4 months they will be worth $450 why would you sell a contract for less?
Someone buying the contract believes the price will be higher, someone selling the contract believes the price will be lower.