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Trading

Exploring the link between behavioural finance and technical analysis

Published by Gbaf News

Posted on October 7, 2011

5 min read

· Last updated: January 22, 2019

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by Bijoy Kar, CFA
Technical Strategist at MIG BANK – a leading Swiss FX and CFDs online trading provider

The Evolution of Security Analysis

The historical starting point for security analysis.
Historically strategists and asset allocation specialists have used macro economics/fundamental analysis, together with the concept of modern portfolio theory (MPT) as their starting point for security analysis.

Initially projections/assumptions are made for major macro statistics like GDP growth, unemployment, inflation etc. These projections are then used to make assumptions about the likely movement in government bond markets and then all other markets that are affected by the repo rate (base rate)
(see figure 1).

Assumptions Underpinning Modern Portfolio Theory

To assess the robustness of any form of analysis we need to take a closer look at any assumptions that are made. In the case of Modern Portfolio Theory, we make some major assumptions about the behaviour of the individuals that operate within financial markets. In particular we assume the following:

  • All investors are rational and risk-averse.
  • All investors have access to the same information at the same time.
  • Investors have an accurate conception of possible returns.
  • Asset returns are normally distributed random variables.
  • There are no taxes or transaction costs.

There are other assumptions but they will not be covered at this point.

Challenges and Limitations in Financial Assumptions

The weakness of assumptions in MPT / The reality of trading.
The following points need to be considered when questioning the above assumptions:

  • Anyone who has traded their own account or worked on a trading floor will know that investment decisions are rarely made under conditions of rationality. Instead fear and greed dominate.
  • There is a clear divide regarding market information when it comes to institutional versus retail investment. Institutional investors are often in receipt of information far in advance of their retail counterparts.
  • Investors often have irrational expectations of possible returns, basing their expectations on an in built human inclination to linearly extrapolate the recent past.
  • Many asset returns are not normally distributed, this is just an assumption that makes the mathematics of risk evaluation easier and is often relatively accurate, however, skewed distributions with fatter tails are more accurate.

Rationality Versus Real-World Trading Behavior

Purely using rational thought and fundamental analysis is unlikely to lead to success, which is why so many computer models have become dominant in the world of trading.
The best way to determine if the above assumptions are close to reality is simply to look at the evidence of investor behaviour from price history.

All of the above economic releases are likely to bias even a rational investor to trade from the long side, but following all of these releases Sterling was bought, forcing EUR/GBP lower. It is clear that fundamental analysis would not have been a great deal of help at this point. Understanding human behaviour would have helped. However, fundamental analysis should not be dismissed. Instead the market reaction to fundamental releases can potentially be used to assist the astute investor in trying to determine the general positioning of the market.

by Bijoy Kar, CFA
Technical Strategist at MIG BANK – a leading Swiss FX and CFDs online trading provider

The historical starting point for security analysis.
Historically strategists and asset allocation specialists have used macro economics/fundamental analysis, together with the concept of modern portfolio theory (MPT) as their starting point for security analysis.

Initially projections/assumptions are made for major macro statistics like GDP growth, unemployment, inflation etc. These projections are then used to make assumptions about the likely movement in government bond markets and then all other markets that are affected by the repo rate (base rate)
(see figure 1).

To assess the robustness of any form of analysis we need to take a closer look at any assumptions that are made. In the case of Modern Portfolio Theory, we make some major assumptions about the behaviour of the individuals that operate within financial markets. In particular we assume the following:

  • All investors are rational and risk-averse.
  • All investors have access to the same information at the same time.
  • Investors have an accurate conception of possible returns.
  • Asset returns are normally distributed random variables.
  • There are no taxes or transaction costs.

There are other assumptions but they will not be covered at this point.

The weakness of assumptions in MPT / The reality of trading.
The following points need to be considered when questioning the above assumptions:

  • Anyone who has traded their own account or worked on a trading floor will know that investment decisions are rarely made under conditions of rationality. Instead fear and greed dominate.
  • There is a clear divide regarding market information when it comes to institutional versus retail investment. Institutional investors are often in receipt of information far in advance of their retail counterparts.
  • Investors often have irrational expectations of possible returns, basing their expectations on an in built human inclination to linearly extrapolate the recent past.
  • Many asset returns are not normally distributed, this is just an assumption that makes the mathematics of risk evaluation easier and is often relatively accurate, however, skewed distributions with fatter tails are more accurate.

Purely using rational thought and fundamental analysis is unlikely to lead to success, which is why so many computer models have become dominant in the world of trading.
The best way to determine if the above assumptions are close to reality is simply to look at the evidence of investor behaviour from price history.

All of the above economic releases are likely to bias even a rational investor to trade from the long side, but following all of these releases Sterling was bought, forcing EUR/GBP lower. It is clear that fundamental analysis would not have been a great deal of help at this point. Understanding human behaviour would have helped. However, fundamental analysis should not be dismissed. Instead the market reaction to fundamental releases can potentially be used to assist the astute investor in trying to determine the general positioning of the market.

Key Takeaways

  • Modern Portfolio Theory relies on unrealistic rational‑investor assumptions which often don’t hold in practice.
  • Behavioural finance highlights biases—like fear, greed, anchoring and extrapolation—that undercut MPT’s assumptions.
  • Technical analysis captures patterns arising from collective investor behaviour shaped by psychological biases.
  • Combining fundamental analysis with behavioural insight and technical tools enhances understanding of market reactions.

References

Frequently Asked Questions

What is Modern Portfolio Theory’s key weakness?
MPT assumes investors are rational, informed, and returns are normally distributed—assumptions often violated by real‑world trading behaviour.
How does behavioural finance improve security analysis?
By accounting for cognitive biases like fear, greed, anchoring and herding, it explains market reactions and inefficiencies not addressed by traditional theory.
What role does technical analysis play alongside behavioural finance?
Technical analysis uses price and volume patterns—reflections of collective investor behaviour—to identify trends and support/resistance levels shaped by bias.
Should fundamental analysis be discarded?
No—fundamentals still matter, but combining them with behavioural and technical perspectives helps interpret market reactions more effectively.

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