Because the economy stopped growing, which means there is little demand for money. If there is a large demand for capital then interest rates will rise. It's ordinary supply and demand only applied to money rather than some good or service.
Wrong side of the equation. There is an oversupply of money, leading to low interest rates.
So yes, there is an oversupply, but that's the same as little demand on the other side of the bank, plus or minus some arbitrary skew in time.
The bank simply tries to make money from being in the middle between supplier of capital (you and your savings) and the consumers of capital (the demand side, industry, mortgages and so on).
Current rates are low because central banks everywhere are basically flooding the world with free money, throwing good money after bad money by monetizing poisonous debt, to prevent the financial system from imploding (which almost happened in 2008). Or at least postpone it for as long as possible. Ben Bernanke will be (almost) the last person on earth to say this out loud, which makes the value of this fluff piece on a site like this pretty dubious. There's a reason why his nickname is 'Helicopter Ben'.
I keep some musings about this here if you are curious: http://bessiambre.tumblr.com/
Just to be clear, I'm not saying Bernanke had easy and/or painless other policy options, or that central banks would even have the ability to fix the global economy and monetary system by the way. Just that a piece like this is a more or less meaningless bedtime story.
Risk adjusted market returns are clearly in negative territory otherwise we wouldn't have these piles of idle reserves even at -2% real return.
> for malinvestments (e.g. the shale oil industry...
Malinvestment is not something that exists under any mathematically consistent macroeconomic model but even if we try to tie the word to a somewhat sensical meaning, the most "malinvested" form of savings, short of using the money to hire people to destroy property, is to keep the savings as excess idle money. Savings have a return of near -100% to the aggregate economy when they are turned into uninvested idle fiat. The returns are even lower than -100% if you consider the welfare paid to the unemployed this results in.
Even if the shale oil industry gets a very poor return of -50% it would still be better for economic value creation than building excess fiat. Of course central banks did not cause the shale oil troubles as they set their rate to imply anything not having at least -2% risk adjusted real returns is not worth doing. Shale oil went way below that because of factors independent of central banks.
If a monetary bubble ends up bursting it will be because central banks have been too tight, making fiat keep its value above market safe returns and getting people and banks to stockpile it instead of investing in the private economy, effectively turning savings into mere intrinsically valueless paper which doesn't have any economic activity, any stuff or means of production to back them.
In 2009, here on HN, people were warning that the first round of QE would lead to Weimar-style hyperinflation in fairly short order. Six years and two additional rounds of QE later, interest rates and inflation in the U.S. are still quite low.
People tend to forget that the economy has done quite well even under inflation levels that we'd now consider high; during the Reagan boom, inflation fluctuated between 3-5%. Even if all this QE led to 5% inflation for a number of years, that's not really a serious problem (and certainly not hyperinflation).
It starts to get painful when you get to 10%, 15%, 20%, but that's a fixable problem. Indeed, it was fixed at the end of the 1970s. It was painful, but it was fixed.
So, yes, it might catch up with us. But when and how badly matter a lot. If the cost of all this QE is that average inflation in the 2020s is 5%, so what? That's hardly a disaster. Or let's say inflation creeps up to about 12%, and in 2025 the Fed takes strong action to get it under control, leading to a sharp painful recession in 2025-26. Should we have a decade or two's worth of stagnation to avoid this hypothetical? I personally don't think so.
If central banks had printed sufficiently and promised to push inflation high enough early in the financial crisis, the market would have cleared and much less money would have accumulated idle in the system overall.
Here are some of my musings on this:
Money is fundamentally an intertemporal thing, and we've known since the 1930s that the cute little supply-demand time-slice diagrams in textbooks don't work on the money supply.
Here we see the prices of 10-year bonds falling (=> interest rates rising) with each QE cycle: http://www.pragcap.com/wp-content/uploads/2013/11/arp1.png
Money at around -2% real return is still pricing private stores of value, read new investment, out of the market. Money needs a real return that is lower than that so that fiat is not over valued compared to market stores of value, and people, banks and businesses don't hold their savings in excess idle reserves instead of in things that have intrinsic value and that are backed by economic activity.