Utilize your financial knowledge, give your answer or opinion to the input question or subject . Answer format is not limited.

Do bond interest rate risk premiums only compensate for the amount investors might lose?
In answer to your last formulation, no. In a perfectly efficient market, different investors still have different risk tolerances (or utility functions). They're maximizing expected utility, not expected value.  The portfolios that maximize expected utility for different risk preferences are different, and thus generally have different expected values. (Look up mean-variance utility for a simple-ish example.)  Suppose you have log utility for money, u(x) = log(x), and your choice is to invest all of your money in either the risk-free bond or in the risky bond. In the risky bond, you have a positive probability of losing everything, achieving utility u(0) = -\infty. Your expected utility after purchase of the risky bond is:  Pr(default)*u(default) + (1-Pr(default))*u(nominalValue).  Since u(default)= -\infty, your expected utility is also negative infinity, and you would never make this investment. Instead you would purchase the risk-free bond.  But another person might have linear utility, u(x) = x, and he would be indifferent between the risk-free and risky bonds at the prices you mention above and might therefore purchase some. (In fact you probably would have bid up the price of the risk-free bond, so that the other investor strictly prefers the risky one.) So two different investors' portfolios will have different expected returns, in general, because of their different risk preferences. Risk-averse investors get lower expected value. This should be very intuitive from portfolio theory in general: stocks have higher expected returns, but more variance. Risk-tolerant people can accept more stocks and more variance, risk-averse people purchase less stocks and more bonds. The more general question about risk premia requires an equilibrium price analysis, which requires assumptions about the distribution of risk preferences among other things. Maybe John Cochrane's book would help with that---I don't know anything about financial economics. I would think that in the setup above, if you have positive quantities of these two investor types, the risk-free bond will become more expensive, so that the risky one offers a higher expected return. This is the general thing that happens in portfolio theory. Anyway. I'm not a financial economist or anything.  Here's a standard introduction to expected utility theory: http://web.stanford.edu/~jdlevin/Econ%20202/Uncertainty.pdf