Perhaps the best way to hedge your portfolio against a crash, is to make sure you always have a healthy portion of it allocated to cash. The amount you allocate to cash really depends on how much volatility you are happy to tolerate. More cash means you stand to lose less, but you will probably lose out on returns in the long run. A lower cash balance will probably lead to higher overall returns, but will also mean higher volatility.
In putting this into practice today, let’s assume we have $100,000 invested in equities currently so we need to buy $500 in 2-month put options (0.5% of $100,000) that are 30% below the current underlying price. SPY trades at 219.4 as I write this so $154 is about 30% beneath this price. A small segment of the October 21 put options chain is below (from Yahoo!Finance). Looking at the ask prices and volume it looks like the 155 puts are a bit more liquid and better priced than the 154 puts. At $9 each (9c times 100 shares) we can buy 55 of the October 155 put options for $495.
Marc, I hope you and your kids can stay in So Cal, but can you see how the money and people are being vilified for wanting to be part of California’s successful economy and lifestyle. The real villains are those who are preventing development. And that new development really drives the economy, thus giving California a chance to compete in the global age. Other cities in Canada and the UK have the same problem and in each case it’s politicians squeezing supply. And the actions they’re taking does point to a recession eventually. If California’s polticians remove constraints, you’ll have lower prices in San Diego, LA and the SF Bay Area. The market alway solves itself.
Bush came into office just as the terrorists mounted their attack. Clinton was the President previously. I think Bush was stunned at the attack just as he was sitting down in the Oval Office. Are you suggesting they attacked because of what they thought Bush might do in future? Half of the debt came with Obama so why is he innocent of all this? Why couldn’t the trillions dished out be tracked? Wouldn’t it have been better spent on badly needed infrastructure spending? Joe, I’m not sure you have a good argument here, but thanks for contributing.
I’m in the market to buy a house in San Diego County and turn it into a vacation rental. I own one and it is very successful. I’m wondering if I should wait to buy, and if a recession would lead to a decrease in vacation rental bookings? I’m concerned and do not want to find myself under water. Any updates on this fascinating chain of discussion as of April, 2018?

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To sum it up, while the Buffett Indicator is certainly a great snapshot of stock valuations, it's not a stand-alone metric that you should use to determine when to buy or sell. When asked about the Buffett Indicator and another favorite metric at Berkshire's 2017 annual meeting, Buffett said that, "It's just not quite as simple as having one or two formulas and then saying the market is undervalued or overvalued."
Good harvests had built up a mass of 250 million bushels of wheat to be "carried over" when 1929 opened. By May there was also a winter-wheat crop of 560 million bushels ready for harvest in the Mississippi Valley. This oversupply caused a drop in wheat prices so heavy that the net incomes of the farming population from wheat were threatened with extinction. Stock markets are always sensitive to the future state of commodity markets, and the slump in Wall Street predicted for May by Sir George Paish arrived on time. In June 1929, the position was saved by a severe drought in the Dakotas and the Canadian West, plus unfavorable seed times in Argentina and eastern Australia. The oversupply would now be wanted to fill the big gaps in the 1929 world wheat production. From 97¢ per bushel in May, the price of wheat rose to $1.49 in July. When it was seen that at this figure American farmers would get rather more for their smaller crop than for that of 1928, stocks went up again.
Following the 1987 stock market crash was one of the major reforms that were introduced was by the Chicago Mercantile Exchange and the NYSE. They together introduced the revolutionary “circuit breaker” mechanism. This system was installed in these two exchanges to that no major market crashes further occurred. What this mechanism did was halt the market in case of major fall of the Dow. During this period no trade could be carried out in these two exchanges. If the Dow fell 250 points or more, the market would stop its trading for an hour. If the fall had been for more than 400 points then the market would halt for two hours.
Japanese asset price bubble 1991 Lasting approximately twenty years, through at least the end of 2011, share and property price bubble bursts and turns into a long deflationary recession. Some of the key economic events during the collapse of the Japanese asset price bubble include the 1997 Asian financial crisis and the Dot-com bubble. In addition, more recent economic events, such as the late-2000s financial crisis and August 2011 stock markets fall have prolonged this period.

Whether Professor Sornette is right or not that a critical point can be anticipated, the entire concept of market self-organization deals a blow to the “fundamental” approach to investing in equity markets – the idea that opinion-based research can lead to investment success when it seems quite apparent that outcomes cannot be predicted even when initial conditions are known.
Secondly, he says, higher interest rates raise borrowing costs for consumers and companies, so auto loans and mortgages become more expensive and companies have a harder time tapping the debt market. "Clearly, higher rates are not good for housing or auto sales," says Ed Yardeni, chief investment strategist at Yardeni Research. And if sales of these big-ticket items slow, so does the broader economy.

“Investing is the attempt to make a financial killing, in other words, bigger profits and less work. Why else would anyone with their head on straignt want to make a profit on the backs of others? Thousands of years ago it was determined by one nation that debts should be forgiven every 7 years. Lending money with large interest rates was unfair. It’s in Egyptian and Abrahamic history.”
The crash began in Far Eastern markets the morning of October 19 and accelerated in London time, largely because London had closed early on October 16 due to the storm. By 9.30am, the London FTSE100 had fallen over 136 points. Later that morning, two U.S. warships shelled an Iranian oil platform in the Persian Gulf in response to Iran's Silkworm missile attack on the Sea Isle City.[3][4]
"If I'm going to rank the risks this fall, trade wars are one. Iran oil sanctions are two, then the European crisis is three. You have the Italian budget, due at the end of September, which is a very contentious thing, where the government promised a budget the European Commission is very likely to reject," said Harris. "I think you've already seen a foretaste with the Italian bond yields spiking up and staying higher."
Fast forward thirty years. I’ve discovered an analog chart model that correlates the markets of the 1980s to the markets of the 2010s. Specifically, it correlates the S&P 500 from 1978 to 1987 to the S&P 500 from 2010 to 2018. The correlation rate? 94%. In other words, this model shows that the stock market of the past eight years is trading similar to the stock market of the 1980s.
Scenario:  Big money chases few homes, and when governments persist in stopping or not supporting land development, speculators become more confident prices will rise further. Then a politician or FED president steps in with their reactive solution, at the end of the business cycle where employment and profits will begin to drop. Speculators/investors pull out fast, and the slide begins.
I’m less concerned than our friends at the Fed. Businesses are rebelling in mass against Trump’s punitive tariffs on steel, aluminum, and lumber. Trump is still blind to his own economic idiocy as I write. Given the torrent of negative press on tariffs in recent weeks, I suspect that a member or two of his retinue will force him to see the light. They’ll force him sooner than later.