I wholeheartedly recommend you add this book to your reading list. It's the best basis I know of for "so you don't understand the stock market, but you understand that you have an IRA and you want to not lose it." In that book, Malkiel pretty much explains all financial behavior as the tension between Fundamentals Theory and Greater Fool Theory (which, per Keynes, he refers to as "Firm Foundation theory" and "Castle in the air theory").

I'm probably going out on a limb here, but I think you could make an analogy between Fundamentals/Greater Fool and Beta/Alpha gains.

Fundamentals Theory postulates that a stock is worth what it's worth, or more, what you'd lose if you didn't have it. If you have a thousand shares of GM, and each share pays out a dollar every quarter, you make four thousand dollars a year off your shares of GM, plus whatever you've made or lost on the difference between when you buy it and when you sell it. From that, you subtract what you'd make if you'd taken the money you've sunk into GM stock and put it in a zero-risk CD and you have the fundamental value of your GM stock - profit minus opportunity cost.

Greater Fool Theory holds that everything above is rubbish - the value of the stock is whatever you can sell it for. Pets.com stock was worth a shit-ton at some point, and nothing at a point shortly thereafter. If you converted your options in Groupon to shares at the IPO, your options were worth whatever you could sell your Groupon shares for, and are now worth dogshit.

By comparison, beta gains are the money you make on a stock just by holding it - because the pooling of resources and the market for capital are multiplicative on the economics of business, and because nobody would buy shares in something if they didn't expect to make it back more often than not, markets have long-term beta gains. A rising tide raises all ships. Beta gains are whatever the market makes. SPY tracks pure beta.

Alpha gains, on the other hand, are money you make at the expense of someone else. A stock that makes an alpha gain is a stock that rises higher than the market, which means that somewhere out there there's a stock that rises lower than the market. For every overperformer there's an underperformer.

Beta gains track what the stock market is "fundamentally" worth, really. Alpha gains track what you can sell it for. They can also track a stock that fundamentally has great value... but the market cap on Tesla is higher than the market cap on GM. Fundamentally, Tesla has never paid a dividend. Fundamentally, Tesla has yet to turn a profit. Fundamentally, GM has been paying a dividend every quarter since nineteen diggity two. But there are plenty of greater fools who will happily pay ten times the price of a share of GM for a share of Tesla. And so long as you can sell your shares to someone else for more than you paid for them, you made money.

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So. Long walk to get to the answer but it's like this: interest rates are an important part of beta gains. When interest rates are high, that means that you make more money just by lending out cash. When interest rates are high, the fundamental value of a stock is lessened because shit, you could make money on CDs or municipal bonds or something equally stable.

Interest rates right now are low which is causing a lot of deviant behavior. It's causing a lot of unstable trades. It's causing a normalization of ideas like of course Tesla is worth ten times as much per share as GM. I've heard it argued that the Seattle housing market is hyperinflated simply because Amazon isn't required to have any profits in order to justify its stratospheric valuation - think about it. Their business model is to suck the profits out of selling things and then make it up on volume. They are literally attempting a monopoly of commerce and the closer they get (until they reach the singularity) the less money they'll make. They're at like a thousand dollars a share.

And you can write all this and go yep, sounds crazy but volatility is down. That means that the perceived craziness of the market is actually dropping. It gets stupider and stupider but by any metric, everybody who trades is going "meh" and going about their business as if Tesla is actually worth $300 a share. It means that the prices of the market are being driven not by fundamentals theory but by greater fool theory -

- which works until there is no greater fool.

The lower the volatility measures, the less the market believes in a limited supply of fools. Actual volatility is pretty goddamn breathtaking:

billions of dollars in market cap spiking because of Trump's verbal diarrhea. That is not the sign of a high-stability market, yet the indicators say the opposite. Supposedly consumer confidence is at an all-time high yet one of my newsletters pointed out that the percentage of Americans who think they'll be able to retire is at an all-time low.

So there's likely to be a correction. And it may not be an elegant one.