What happens if it resolves 1/2? Does everyone mana gets returned? Or those who bid when it was lower than 50% for either team get more?

both options resolve to 50% probability

I you bought YES at 60%, you lose a little money; if you bought at 40%, you win a little.

I can't get it to exactly 50/50.

you're just losing mana on trading fees, lol

china has almost completed, only one weightlifting left. us has two left, women's basketball and women's volleyball. could be a tie.

Not true. US also has a weightlifting event and a wrestling final.

i mean events that higher chance win gold. but yes, the possibility to pass china is still higher for US.

Perhaps I am just ignorant, but the countries are currently tied for gold medals and the Olympics is almost over. Why is the US favored so strongly? Are there a lot of tail-end events in which the US is heavily favored?

My understanding is yes. But I don't know much about the Olympics.

What are the best sources to use for this?

I don't follow Olympics very closely, can someone explain the current market? China currently has 8 gold to USA's 4- are there a lot of events the US is by far the favourite to place first in coming up? Why are China's odds so low?