After a rocky first quarter markets posted a solid second quarter and improved steadily through the third quarter. The US economy is currently rolling along at a pretty healthy pace as GDP grew at 4.2% in the second quarter and earnings have been strong. Unemployment clocked in at 3.7% for September which is incredibly low by historical standards. Indications of inflation are starting to creep into wages, materials, and transportation and many manufacturers have been able to offset them by raising prices. Through the lens of economics, investors are in good shape.

It wasn't that long ago, however, that investors looked past a feeble economic recovery and took cheer in the large volumes of liquidity major central banks around the world infused to support financial assets. Now the time has come to reverse course. As the

Economist states [here] in no uncertain terms, "Central banks are pitiless executioners of long-lived booms and monetary policy has shifted." Investors who view these conditions exclusively through the lens of economics risk misreading this pivotal event: global liquidity is falling and will bring asset prices down with it.

Liquidity is one of those finance topics that often gets bandied about but it is often not well understood. It seems innocuous enough but it is critical to a functioning economy. In short, it basically boils down to cash. When there is more cash floating around in an economic system, it is easier to buy things. Conversely, when there is less, it is harder to buy things.

Chris Cole from Artemis Capital Management has his own views as to why investors often overlook liquidity [here]. He draws an analogy between fish and investors. Because fish live in water, they don't even notice it. Because investors have been living in a sea of liquidity, they don't even notice it. As he notes, "The last decade we’ve seen central banks supply liquidity, providing an artificial bid underneath markets."

Another aspect of liquidity that can cause it to be under appreciated is that it is qualitatively different at scale. A drop of water may be annoying, but it rarely causes harm. A tsunami is life-threatening. Conversely, a brief delay in getting a drink of water may leave one slightly parched, but an extended stay in the desert can also be life-threatening. We have a tendency to take water (and liquidity) for granted until confronted with extreme conditions.