The US stock markets enjoyed an extraordinary surge in 2017, shattering all kinds of records. This was fueled by hopes for big tax cuts soon since Republicans regained control of the US government. But such relentless rallying has catapulted complacency, euphoria, and valuations to dangerous bull-slaying extremes. This has left today’s beloved and lofty stock markets hyper-risky, with serious selloffs looming large.

History proves that stock markets are forever cyclical, no trend lasts forever. Great bulls and bears alike eventually run their courses and give up their ghosts. Sooner or later every secular trend yields to extreme sentiment peaking, then the markets inevitably reverse. Popular greed late in bulls, and fear late in bears, ultimately hits unsustainable climaxes. All near-term buyers or sellers are sucked in, killing the trend.

This mighty stock bull born way back in March 2009 has proven exceptional in countless ways. As of mid-December, the flagship S&P 500 broad-market stock index (SPX) has powered 297.6% higher over 8.8 years! Investors take this for granted, but it’s far from normal. That makes this bull the third-largest and second-longest in US stock-market history. And the superior bull specimens vividly highlight market cyclicality.

The SPX’s biggest and longest bull on record soared 417% higher between October 1990 and March 2000. After it peaked in epic bubble-grade euphoria, the SPX soon yielded to a brutal 49% bear market over the next 2.6 years. The SPX wouldn’t decisively power above those bull-topping levels until 12.9 years later in early 2013, thanks to the Fed’s unprecedented QE3 campaign! The greatest bull ended in tears.

The second-largest bull was a 325% monster between July 1932 to March 1937. But that illuminated the inexorable cyclicality of stock markets too, as it arose from the ashes of a soul-crushing 89% bear in the aftermath of 1929’s infamous stock-market crash. Seeing today’s central-bank-inflated bull balloon to such monstrous proportions rivaling the greatest stock bulls on record highlights how extreme it has become.

All throughout stock-market history, this binary bull-bear cycle has persisted. Though some bulls grow bigger and last longer than others, all eventually give way to subsequent bears to rebalance sentiment and valuations. So stock investing late in any bull market, which is when investors complacently assume it will last indefinitely, is hyper-risky. Bear markets start at serious 20% SPX losses, and often approach 50%!

Popular psychology in peaking bull markets is well-studied and predictable. Investors universally believe “this time is different”, that some new factor leaves their bull impregnable and able to keep on powering higher indefinitely. This new-era mindset fuels extreme euphoria and complacency, with memories of big selloffs fading. Investors’ hubris swells, as they forget markets are cyclical and ridicule any who dare warn.

To any serious student of stock-market history, there’s little doubt today’s stock-market situation feels exactly like a major bull-market topping. All the necessary ingredients are in place, ranging from extreme greed-drenched sentiment to extreme bubble valuations literally. If this bull was merely normal, the risks of an imminent countertrend bear erupting to eradicate these late-bull excesses would absolutely be stellar.

But the downside risks in the wake of this exceptional bull are far greater than usual. That’s because much of this bull is artificial, essentially a Fed-conjured illusion.  And that was even before the incredible 2017 taxphoria surge in the wake of Trump’s surprise victory! Back in early 2013 as the SPX was finally regaining its previous bull’s peak, the Fed unleashed its wildly-unprecedented open-ended QE3 campaign.

Understanding the Fed’s role in fomenting this anomalous stock bull is more important than ever. Not only is the Fed deep into its 12th rate-hike cycle of the past half-century or so, it has begun quantitative tightening for the first time ever. This QT is starting to unwind the trillions of dollars of QE that levitated the stock markets for years. While QT started small in Q4’17, it’s ramping to a $50b-per-month pace in Q4’18!

The Fed’s QE giveth, so the Fed’s QT taketh away. Literally trillions of dollars of capital evoked out of nothing by the Fed to monetize bonds, directly and indirectly, bid stock markets higher. The Fed’s deep intertwinement in this stock bull’s fortunes is easiest to understand with a chart. Here the SPX in blue is superimposed over its implied-volatility index, the famous VIX that acts as a proxy for popular greed and fear.

This anomalous stock bull was again birthed in March 2009 in the wake of the first true stock panic since 1907. After that epic maelstrom of fear-fueled such an extreme plummet to climax a 57% bear market, a new bull was indeed overdue despite rampant bearishness and pessimism. The very trading day before the SPX bottomed, I wrote a hardcore contrarian essay explaining why a major new bull market was imminent.

Back in early 2009 stock-market valuations were so low after the panic that a new bull was fully justified fundamentally. And its first four years or so played out perfectly normal. Between early 2009 to late 2012, this bull market’s trajectory was typical. It rocketed higher initially out of deep bear lows, but those gains moderated as this bull matured. And its upside progress was punctuated by healthy major corrections.

Stock-market selloffs are generally defined in set ranges. Anything under 4% isn’t worth classifying, it is just normal market noise. Then from 4% to 10%, selloffs become pullbacks. Beyond that in the 10%-to-20% range are corrections. Selloffs greater than 20% are formally considered bear markets. In both 2010 and 2011, the SPX suffered major corrections in the upper teens, which are essential to rebalance sentiment.

As bull markets power higher, greed naturally grows among investors and speculators. They start to get very complacent and expect higher stocks indefinitely. Eventually, this metastasizes into euphoria and even hubris. Major corrections, big and sharp mid-bull selloffs, rekindle fear to offset excessive greed and keep bulls healthy. Interestingly even in 2010 and 2011, the Fed played a key role in stock-market timing.

Those early bull years’ major corrections coincided exactly with the ends of the Fed’s first and second quantitative-easing campaigns. QE is an extreme monetary-policy measure central banks can use after they force interest rates, their normal tool, down to zero. The Fed’s zero-interest-rate policy went live in mid-December 2008 in response to that first stock panic in a century, and QE1 then QE2 soon followed.