Right now loans are based on the mana you put into the market; your cost basis. Many people have suggested changing them to pay out based on the current share value instead.

Edit: The new system pays out based on cost basis if the market price is above your cost basis, and based on market value if it's below. On average across many markets, this means about half your loans will be on cost basis and the other half with be on the current share value. So if the system doesn't change again before the end of the year, 50% seems like the most appropriate resolution to me. Feel free to present counterarguments if you disagree.