From John Hussman, here:
So passive buy-and-hold investors – who lock in a price and don’t alter their investment positions for a long period of time – should recognize that Treasury bonds are likely to outperform stocks over the coming decade, with substantially less risk. In my view, neither asset class is attractively priced, but in a world of zero returns on Treasury bills, our risk budget for passive investors would lean more toward bonds than equities here nonetheless.