Low-volatility investing is an investment style that buys stocks or securities with low volatility and avoids those with high volatility. This investment style exploits the low-volatility anomaly. According to financial theory risk and return should be positively related, however in practice this is not true. Low-volatility investors aim to achieve market-like returns, but with lower risk. This investment style is also referred to as minimum volatility, minimum variance, managed volatility, smart beta, defensive and conservative investing.

The low-volatility anomaly was already discovered in the early 1970s, yet it only became a popular investment style after the 2008 global financial crises. The first tests of the Capital Asset Pricing Model (CAPM) showed that the risk-return relation was too flat.^[1][2] Two decades later, in 1992 the seminal study by Fama and French clearly showed that market beta (risk) and return were not related when controlling for firm size.^[3] Fisher Black argued that firms or investors could apply leverage by selling bonds and buying more low-beta equity to profit from the flat risk-return relation.^[4] In the 2000s more studies followed, and investors started to take notice.^[5][6][7] In the same period, asset managers such as Acadian, Robeco and Unigestion started offering this new investment style to investors. A few years later index providers such as MSCI and S&P started to create low-volatility indices.

Low-volatility investing is gradually gaining acceptance due to consistent real-life performance over more than 15 years, encompassing both bull and bear markets. While many academic studies and indices are based on simulations going back 20-30 years, some research spans over 90 years, showing low-volatility stocks outperform high-volatility stocks in the long run (see image). Since low-volatility securities tend to lag during bull markets and tend to reduce losses in bear markets, a full business cycle is needed to assess performance. Over shorter time periods, such as one year, Jensen's alpha is a useful performance metric, adjusting returns for market beta risk. For instance, a low-volatility strategy with a beta of 0.7 in a 10% rising market would be expected to return 7%. If the actual return is 10%, Jensen's alpha is 3%.

Any investment strategy can lose effectiveness over time if its popularity causes its advantage to be arbitraged away. This could apply to low-volatility investing, highlighted by the high valuations of low-volatility stocks in the late 2010s.^[8] Still, David Blitz showed that hedge funds are at the other side of the low-volatility trade, despite their ability to use leverage. Others state that low-volatility is related to the well-known value investing style. For example, after the dotcom bubble, value stocks offered protection similar to low volatility stocks. Additionally, low-volatility stocks also tend to have more interest rate risk compared to other stocks.^[9] 2020 was a challenging year for US low-volatility stocks as they significantly lagged behind the broader market by wide margins.^[10][11] Criticism and discussions are primarily found in various academic financial journals, but investors take notice and contribute to this debate.^[12][13]

• Low-volatility anomaly
• Investment style / Style investing
• Value investing
• Momentum investing

A couple of books have been written about low-volatility investing:

• Eric Falkenstein, Wiley Publishers 2011, Finding Alpha: The search for alpha when risk and return break down. ISBN 9780470445907
• Peter Sander, McGraw-Hill 2013, All about low-volatility investing. ISBN 9780071819848.
• Eric Falkenstein, 2016, The Missing Risk Premium: Why low-volatility investing works. ISBN 1470110970
• Pim van Vliet, Jan de Koning, Wiley Publishers 2017, High Returns from Low Risk: A Remarkable Stock Market Paradox. ISBN 9781119351054.