The FRED data series BUSLOANS shows the commercial and industrial loans from all commercial banks. Business loan volume grew steadily up until about 1975, turned up significantly through the 1980s, and then absolutely exploded after 1993. The prosperity of the Clinton years wasn't just a function of PCs and the Internet making business more productive. It was also a function of debt-fueled business spending on IT infrastructure, physical plant, and even M+A activity. Loan volume has almost matched its late 2008 peak.
The raw data from the NYSE is just as stark. Dig deep for "securities market credit" and note how margin debt has exploded since 2010. Hedge funds at the big end and retail investors at the small end are leveraging their accounts and trading like mad. The explosion in C+I debt above is fueling traders' madness. Corporations use debt for stock buybacks, special dividends, and poorly chosen M+A deals that inflate their enterprise values. Investors chase these phantom growth drivers at their peril.
The growth in business loans and securities market credit is unsustainable. Both figures have outstripped GDP growth and population growth at least since the 2008 crisis. Corporations carrying huge loans and investors carrying huge margins will all feel enormous pain when the market reverses course. People going nuts about perpetual economic expansions need to get sober. They definitely need schooling on how excess debt kills the thrill of investing when downturns hit.