Dent is the Founder of HS Dent Investment Management, an investment firm based in Tampa, Florida that advises, and markets, the Dent Strategic Portfolio Fund mutual fund. Dent is also the president and founder of the Dent Research and H.S. Dent Publishing.
Dent writes and markets an economic newsletter that reviews the economy in the US and around the world by focusing on generational consumer spending patterns, as well as financial markets. He has written nine books, two recent ones being bestsellers.
The basis of Dent's investment thesis, spending wave theory, is that consumer spending related to the generational formation of families has a profound effect on the market value of investments such as financial securities, real estate, and gold. Dent's spending wave theory posits that young adults spend little within the greater economy, and spending increases while they rear children. It peaks as children leave home and then slows during the last 15 years of working life (48-63). According to Dent, the decreased spending patterns of the current generation of US Baby boomers entering retirement will cause a pronounced downturn in the greater macroeconomy and an associated decline in the value of financial markets.
Forecasts and performance
In the late 1980s, Dent forecast that the Japanese economy, then the darling of the world, would soon enter a slowdown that would last more than a decade. In the early 1990s, he predicted that the DJIA would reach 10,000. Both of these predictions were met with much skepticism, and yet both eventually came to pass.
In Japan, Dent was using their peak of 45- to 50-year-olds (1990–1994) as the beginning of a long slowdown. In the US, he used, and continues to use, the peak year for 48-year-olds, 2009, as the top of a long term growth pattern.
In June 1999 AIM Dent Demographics Fund had significant first year gains, however it performed afterwards until it was ultimately merged into another AIM offering in July 2005 .
In 2000, based on his forecast that economic growth would continue throughout the 2000s, Dent predicted that the DOW would reach 40,000, a prediction which was repeated in his 2004 book. In his book, he also predicted the NASDAQ would reach 13,000 - 20,000. In late 2006 he revised his forecasts to much lower levels, estimating the Dow would reach 16,000 - 18,000 and the NASDAQ 3,000 - 4,000. In January 2006, he predicted that the DOW would reach 14,000 - 15,000 by the end of the year. It ended 2006 at 12,463, 11% below the lower end of his prediction. It ended 2007 at 13,264, again significantly lower than Dent's revised prediction of 15,000 by early 2008. Since then, the Dow crossed 14,000 in late 2007 before retreating.
His 2011 book goes on to suggest consumer spending will begin to plummet in 2012 with the Dow bottoming out somewhere between 3,000 and 5,600 in 2014. After hitting bottom, stocks will experience a mini-rally in 2015-2017 before falling into a final bottom during the 2019-2023 period, when the 45-50 age group troughs because the U.S. birth rate reached its own low in 1973.
In 2012 the "Dent Tactical Advantage ETF," symbol DENT, was de-listed having consistently under-performed the market for three years while at the same time charging an egregiously high 1.65% management fee.
In 2012 he began writing weekly articles for the free investment newsletter Survive & prosper, now known as: Economy & Markets, which offers investment advice guided by his belief that a major economic crash is inevitable and that it will drop the DOW all the way to 3,300. As of early 2013, he has amended his predictions slightly to an expectation that the financial crash will begin between the end of 2013 and the first half of 2014.
In 2013 Dent predicted the market would crash again in the Summer of 2013 and would take a further year and a half to recover.
In 2014, while promoting his book The Demographic Cliff in Australia, he predicted a major Australian housing market correction beginning in 2014 after an even bigger one in China. He also predicted that the price of gold would fall to USD$700 an ounce, and has since revised this prediction to 2015.
Jeffrey M. Laderman suggests in a Bloomberg Businessweek article that, "Harry's explanation of the stock market is a simple one that resonates with investors"..."But is it too simple to explain something as complex as the stock market and the economy?" 
Larry Swedroe, writing for CBS Money Watch asks, "Why do people listen to Harry Dent in light of his obvious inability to accurately predict the future?"
Marketwatch Columnist Chuck Jaffe opines that, tell "people what they want to hear, and they will flock to your door."
- The Demographic Cliff: How to Survive and Prosper During the Great Deflation of 2014-2019 (2014)
- The Great Crash Ahead (2011)
- The Great Depression Ahead (2009)
- The Next Great Bubble Boom (2006)
- The Roaring 2000s Investor (1999)
- The Roaring 2000s (1998)
- The Great Jobs Ahead (1995)
- The Great Boom Ahead (1993)
- Our Power to Predict (1989)
- Siegel, Jeremy J. (2002-06-21). Stocks for the Long Run: The Definitive Guide to Financial Market Returns and Long-Term Investment Strategies, 3rd edition. New York: McGraw-Hill, 388 pp. ISBN 978-0-07-137048-6.
- Jim Fink. "Harry Dent and Demographic Investing: Concept Better than Reality". InvestingDaily.com. Retrieved 2012-02-19.
- Collett, John (2014-02-13). "Nightmare vision of impending property crash". The Sydney Morning Herald. Retrieved 2014-02-14.