Studie: "Trading Is Hazardous to Your Wealth: The Common Stock Investment Performance of Individual Investors" (2000) av Barber och Odean

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Källa: https://faculty.haas.berkeley.edu/odean/papers%20current%20versions/individual_investor_performance_final.pdf

Abstract

Individual investors who hold common stocks directly pay a tremendous performance penalty for active trading. Of 66,465 households with accounts at a large discount broker during 1991 to 1996, those that trade most earn an annual return of 11.4 percent, while the market returns 17.9 percent. The average household earns an annual return of 16.4 percent, tilts its common stock investment toward high-beta, small, value stocks, and turns over 75 percent of its portfolio annually.

Overconfidence can explain high trading levels and the resulting poor performance of individual investors. Our central message is that trading is hazardous to your wealth.

Conclusion

Delar:

We document that the gross returns before accounting for transaction costs! earned by these households are quite ordinary, on average. Unfortunately, the net returns ~after accounting for the bid-ask spread and commissions paid by these investors! earned by these households are poor. The average household underperforms a value-weighted market index by about 9 basis points per month or 1.1 percent annually!

. After accounting for the fact that the average household tilts its common stock investments toward small value stocks with high market risk, the underperformance averages 31 basis points per month or 3.7 percent annually!.

The average household turns over approximately 75 percent of its common stock portfolio annually. The poor performance of the average household can be traced to the costs associated with this high level of trading.

samt

The investment experience of individual investors is remarkably similar to the investment experience of mutual funds. As do individual investors, the average mutual fund underperforms a simple market index. Mutual funds trade often and their trading hurts performance . But trading by individual investors is even more deleterious to performance because individuals execute small trades and face higher proportional commission costs than mutual funds.

Slutsatsen är tydlig:

Our main point is simple: Trading is hazardous to your wealth.

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Jösses! Genomsnittligt innehav 1.3 år. Undrar vad det är i Sverige. Får testa Google på det :slight_smile:

Tur jag kör buy & hold typ för alltid på den mindre delen av totala kapitalet som är enskilda aktier!

EDIT: Googling gav att vi nog har ett annat problem i Sverige mht aktieportföljer. Sannolikt inte för hög omsättning. Däremot sjukt koncentrerade portföljer. En helt annan risk alltså.

I genomsnitt ägde svenska aktieägare 4,5 olika aktieslag i sin portfölj. En liten ökning med 0,4 aktier från 2019. Backar vi tio år tillbaka i tiden låg snittet på 3 olika bolag.

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Jättespännande data. Men hade varit ännu mer intressant med ny data. Finns det nån nyare studie på ämnet?

Jag gissar att courtage är mycket billigare nu (eller t.o.m. gratis i USA med Robinhood). Och det finns en hel del raketer som länge har varit favoriter hos småsparare (krypto, tesla, bitcoin, evolution, sinch).

Eller är det lika vanligt (eller vanligare?) att småsparare investerar i sjunkande skepp som SAS/Norwegian och Oscar Properties?

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Har inte sett någon riktigt likadan studie, men de har ju den här:

We argue that the combination of simplified information display and inexperience exacerbate attentiondriven buying by Robinhood users. Heightened attention-driven buying leads to more concentrated trading by Robinhood users than other retail investors and contributes to buy-side herding events that are usually followed by negative returns.

For example, the top 0.5% of stocks bought by Robinhood users each day experiences negative average returns of approximately 5% over the next month. More extreme herding events are followed by negative average returns of almost 20%.

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