Why are U.S. Treasury interest rates are so low vs. other nearly risk-free rates?
As I'm sure you are reading in Hull's classic, the basic valuation of bonds depends on the chance of entity defaulting on those bonds.  Let's start with just looking at the US.  The United States has a big advantage over corporations in issuing debt as it also prints the same currency that the debt is denominated in.  This makes it much easier not to default on your debt as you can always print more money to pay it.  Printing too much currency would cause inflation lowering the value of debt, but this would also lower the value of US corporate debt as well.  So you can think of even the highest rated corporate bonds as having the same rate as government debt plus a little extra due to the additional default risk of the corporation. The situation with other AA rated governments is more complicated.  Most of those governments have debt denominated in their local currency as well so it may seem like they should all have similar rates.  However, some governments have higher and some actually have lower rates than the United States.  Now, as above, some of the difference is due to the possible need of printing too much currency to cover the debt in crisis and now that we have more than one country to invest in the extra risk of international money flowing out of the country's bonds. However, the bigger difference between AA governments rates depends more on money flow, central banks and regulation.  Bonds are still mostly freely traded instruments that respond to supply and demand, but this supply and demand is heavily influenced by governments.  Central banks buy up large portions of the debt raising demand and lowering rates.  Regulators force banks to hold a certain amount of treasuries perhaps inflating demand. Finally, to answer your question the United States has some interesting advantages partially just due to its long history of stability, controlled inflation and large economy making treasuries valuable as one of the lowest risk investments.  So its rates are generally on the low end, but government manipulation can still mean that it is not necessarily the lowest.
so this is a loan for a house? a loan on a house? a new mortgage? you shouldn't just get a loan for the hell of it any time. interests rates are low because the yields on US treasuries have been pushed closer to zero, and thats pretty much that. the risk is on the bank that approves the loan, and not you. (your ability to repay should be truthful, but your payments are smaller because the interest is so low) It depends how much risk you're prepared to accept. The short-term risk-free rate of return at present is something in the vicinity of 0.1% (three month US treasuries are currently yielding 0.08%), so anything paying a higher rate on money that's accessible quickly will involve some degree of risk -- the higher the rate then the higher the risk. "The fact that some asset (in this case corporate bonds) has positive correlation with some other asset (equity) doesn't mean buying both isn't a good idea.  Unless they are perfectly correlated, the best risk/reward portfolio will include both assets as they will sometimes move in opposite directions and cancel out each other's risk.  So yes, you should buy corporate bonds.  Short-term government bonds are essentially the risk-free asset.  You will want to include that as well if you are very risk averse, otherwise you may not.  Long-term government bonds may be default free but they are not risk free.  They will make money if interest rates fall and lose if interest rates rise.  Because of that risk, they also pay you a premium, albeit a small one, and should be in your portfolio. So yes, a passive portfolio (actually, any reasonable portfolio) should strive to reduce risk by diversifying into all assets that it reasonably can.  If you believe the capital asset pricing model, the weights on portfolio assets should correspond to market weights (more money in bonds than stocks).  Otherwise you will need to choose your weights.  Unfortunately we are not able to estimate the true expected returns of risky assets, so no one can really agree on what the true optimal weights should be.  That's why there are so many rules of thumb and so much disagreement on the subject.  But there is little or no disagreement on the fact that the optimal portfolio does include risky bonds including long-term treasuries. To answer your follow-up question about an ""anchor,"" if by that you mean a risk-free asset then the answer is not really.  Any risk-free asset is paying approximately zero right now.  Some assets with very little risk will earn a very little bit more than short term treasuries, but overall there's nowhere to hide--the time value of money is extremely low at short horizons.  You want expected returns, you must take risk." The literal answer to your question 'what determines the price of an ETF' is 'the market'; it is whatever price a buyer is willing to pay and a seller is willing to accept. But if the market price of an ETF share deviates significantly from its NAV, the per-share market value of the securities in its portfolio, then an Authorized Participant can make an arbitrage profit by a transaction (creation or redemption) that pushes the market price toward NAV. Thus as long as the markets are operating and the APs don't vanish in a puff of smoke we can expect price will track NAV. That reduces your question to: why does NAV = market value of the holdings underlying a bond ETF share decrease when the market interest rate rises?  Let's consider an example. I'll use US Treasuries because they have very active markets, are treated as risk-free (although that can be debated), and excluding special cases like TIPS and strips are almost perfectly fungible. And I use round numbers for convenience. Let's assume the current market interest rate is 2% and 'Spindoctor 10-year Treasury Fund' opens for business with $100m invested (via APs) in 10-year T-notes with 2% coupon at par and 1m shares issued that are worth $100 each. Now assume the interest rate goes up to 3% (this is an example NOT A PREDICTION); no one wants to pay par for a 2% bond when they can get 3% elsewhere, so its value goes down to about 0.9 of par (not exactly due to the way the arithmetic works but close enough) and Spindoctor shares similarly slide to $90. At this price an investor gets slightly over 2% (coupon*face/basis) plus approximately 1% amortized capital gain (slightly less due to time value) per year so it's competitive with a 3% coupon at par.  As you say new bonds are available that pay 3%. But our fund doesn't hold them; we hold old bonds with a face value of $100m but a market value of only $90m. If we sell those bonds now and buy 3% bonds to (try to) replace them, we only get $90m par value of 3% bonds, so now our fund is paying a competitive 3% but NAV is still only $90.  At the other extreme, say we hold the 2% bonds to maturity, paying out only 2% interest but letting our NAV increase as the remaining term (duration) and thus discount of the bonds decreases -- assuming the market interest rate doesn't change again, which for 10 years is probably unrealistic (ignoring 2009-2016!). At the end of 10 years the 2% bonds are redeemed at par and our NAV is back to $100 -- but from the investor's point of view they've forgone $10 in interest they could have received from an alternative investment over those 10 years, which is effectively an additional investment, so the original share price of $90 was correct. Asset prices are inversely related to interest rates. If you're valuing a business or a bond, if you use a lower interest rate you get a higher valuation.  Historic equity returns benefit from a falling interest rate environment which won't be repeated as interest rates can only go so low.  edit: typo It can be zero or negative given the current market conditions. Any money parked with treasury bonds is 100% risk free. So if I have a large amount of USD, and need a safe place to keep, then in today's environment even the banks (large as well) are at risk. So if I park my money with some large bank and that bank goes bankrupt, my money is gone for good. After a long drawn bankruptcy procedure, I may get back all of it or some of it. Even if the bank does not go bankrupt, it may face liquidity crises and I may not be able to withdraw when I want.  Hence it's safer to keep it in Treasury bonds even though I may not gain any interest, or even lose a small amount of money. At least it will be very safe.   Today there are very few options for large investors (typically governments and institutional investors.) The Euro is facing uncertainty. The Yuan is still regulated. There is not enough gold to buy (or to store it.) Hence this leads towards the USD.  The very fact that USD is safe in today's environment is reflected in the Treasury rates. "I'll answer your question, but first a comment about your intended strategy.  Buying government bonds in a retirement account is probably not a good idea.  Government bonds (generally) are tax advantaged themselves, so they offer a lower interest rate than other types of bonds.  At no tax or reduced tax, many people will accept the lower interest rate because their effective return may be similar or better depending, for example, on their own marginal tax rate.  In a tax-advantaged retirement account, however, you'll be getting the lower interest without any additional benefit because that account itself is already tax-advantaged. (Buying bonds generally may be a good idea or not - I won't comment on that - but choose a different category of bonds.) For the general question about the relationship between the Fed rate and the bond rate, they are positively correlated.  There's not direct causal relationship in the sense that the Fed is not setting the bond rate directly, but other interest bearing investment options are tied to the Fed rate and many of those interest-bearing options compete for the same investor dollars as the bonds that you're reviewing.  That's at a whole market level.  Individual bonds, however, may not be so tightly coupled since the creditworthiness of the issuing entity matters a lot too, so it could be that ""bond rates"" generally are going up but some specific bonds are going down based on something happening with the issuer, just like the stock market might be generally going up even as specific stocks are dropping. Also keep in mind that many bonds trade as securities on a secondary market much like stocks.  So I've talked about the bond rate.  The price of the bonds themselves on the secondary market generally move opposite to the rate.  The reason is that, for example, if you buy a bond at less than face value, you're getting an effective interest rate that's higher because you get the same sized incremental payments of interest but put less money into the investment.  And vice versa." Gundlach shared a chart that showed how investors in European “junk” bonds are willing to accept the same no-default return as they are for U.S. Treasury bonds. In other words, the yield on European “junk” bonds is about the same—between 2 percent and 3 percent—as the yield on U.S. Treasuries, even though the risk profile of the two could not be more different.  Sounds like a strong indicator to me. How might this play out in the US?