How would you prepare for a massive stock market crash?

You have 5 years advanced warning of a huge stock market crash. What steps would you take to make sure that you save everything you have invested? Would you buy antiques or gold? Would you avoid banks, pensions, gilds and shares altogether? This is all hypothetical but I am considering how to invest in the future...

stuff all my money under the matress.

save lots of cash so that you can buy when assets are under value after panic sell

Have a good cash reserve and diversify heavily. The nature of the beast is such that when one sector goes down another goes up.

Well, just to humor you: if you knew when the market would crash, I'd short a bunch of stocks or ETFs, and buy bonds and fixed investments. You could also buy some "put options" on large company stock.

Gold/antiques do not have a high correlation to the stock market, so that wouldn't do much for you.

This, unfortunately, is an unrealistic scenario. Your base assumption is that you had "advanced warning of a stock market crash." And that is impossible. No one ever knows if/when the market will crash, regardless of what you may read in the news or from some self-described guru. And trying to "time the market" is the number one reason most investors underperform.

So the more practical answer is simple: if you fear that the market may turn around in the next few years.... DIVERSIFY. Make sure you don't have all your eggs in one basket. Have some large/mid/small cap stocks, some bonds, some international, some alternatives. And use mutual funds or ETFs to spread out your risk.

Short!

short stocks, option puts, hedge funds would be my place to go. You should not have to worry about banks since ur money is insured by the gov. past that, theres not much more u can do. No doubt companies will crash left and right but shorting will put you on the top.

sell all your shares.

Not sure how I'd get this 'advance warning' but if nobody else knew, I'd do my best to sell my knowledge of what was about to happen, coupled with moving all my investments into cash funds as crash-day approached....

Pensions - why avoid them? You just choose suitable funds which, in this case, would mirror an overall strategy aimed at riding out such a crash.

Just before the crash, I would sell all my stocks and other equity investments. Then, I would buy a bunch of bonds.

Put it all into treasuries.

Costless collars (options) and puts.

In a true stock market crash, you would not want to have any money in a bank or in treasuries. However, if you had to invest money in the stock market, even knowing that it would crash in 5 years, I would invest in commodities such as: Gold, Silver, Copper, Coal, These are all things that rarley ever decrease in value, therefore you could always sell for them for more than you bought them for.

well based on the great depression.....
i would pay down debt... hoard cash... not physical bills but i'dmax out savings accounts underneath FDIC limits.
Deflation crushes ALL assets .. even gold.
i'd also hoard canned goods and ammunition.

but this is pure mind game