WEBVTT

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And the last video we have seen that there is or there should be a linear relationship between systematic

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risk and return.

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And we are actually only one step away from the Capital Asset Pricing Model at least from the cap and

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formula.

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And again we are not deriving the Capital Asset Pricing Model here and we do not take any assumptions.

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We are just looking at historical data and try to identify some parents in our historical data.

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So this is actually the graph that we derived in the last video and we have here on the x axis that

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is systematic risk and covariance units and actually covariance is maybe not the most comfortable way

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to display systematic risk and therefore we could also normalize our core variances by dividing each

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covariance by the variance of the market portfolio and by doing so we are actually normalizing the systematic

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risk in a way that we have a systematic risk of one for the market portfolio.

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So let's have a look here and we are still important.

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The summary data frame and here we have the columns systematic risk and variance are covariance terms

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and what we want to do now we want to normalize each and every element here and divide each element

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by the variance of the market portfolio.

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So this is exactly what we are doing here and let's have a look.

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Here we have the normalized systematic risk and we are fair value of 1 for the market portfolio then

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for Amazon we have a higher systematic risk of one point to 2 and for example for Coca-Cola we have

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quite a low systematic risk of 0 point to 5 and actually this normalized a systematic risk metric is

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actually the popular and very famous beta effect or and we can also create a new column here and our

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summary data frame called beta and we exactly are using these values here.

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So let's do this

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so here we have the new column beta and now we can again plot the systematic risk versus the return

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by using here the beta on the x axis and the return on the y axis.

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So let's do this here

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and let's have a look.

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Here we have the beta on the x axis and the market portfolio as a paid off one here and we have further

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return on the y axis and still of course we can see here the linear relationship between systematic

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risk and return.

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So the constituents of the optimal portfolio Boeing Microsoft and Amazon and the optimal portfolio our

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market portfolio itself.

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So they are all here on the one line and this line actually links the risk free asset and the market

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portfolio.

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And again we can also see here that the Coca-Cola stock that Disney's stock and the IBM stock they are

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below the line here because they're actually underperforming and actually in the Capital Asset Pricing

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Model.

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This line is called the security market line and in the optimal world actually each security should

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lie on this line here and in other words each security should actually deliver the return corresponding

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to its systematic risk.

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So we feel a line.

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And if we recall some high school math then we can also derive the equation for that line here.

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And in general the equation for a line looks as follows.

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So y equals to the intercept plus the slope times X and transferring this to our case here.

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So our Y is actually the return of our security is then the intercept with the y axis is actually the

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risk free asset at one point seven percent.

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Then we have here the slope and the slope is actually that y divided by that X and Y is actually the

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mark at portfolio return minus the risk free rate and that X is actually 1 minus 0 is 1.

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So the slope of the security line is simply the market portfolio return minus the risk free return which

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is also called the market excess return.

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And finally our x axis is actually the beta.

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So this is actually the formula to calculate the return of a security given the security is better.

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And this is exactly the Capital Asset Pricing Model formula.

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And we can also cross-check this for example for the Amazon stock.

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So we want to calculate here the Amazon stock return based on its beta and therefore we take you the

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risk free return.

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Then we are calculating here the market portfolio return minus the risk free return.

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And then we finally multiply here with the Amazon beta factor.

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So let's have a look.

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And we get to thirty point one percent and let's have a look at our summary data frame.

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So this is exactly the return that we have here and our historical data thirty one point five percent

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and we can also calculate for each and every stock and also for the market portfolio the return based

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on our formula here.

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So the cap m return.

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So let's do this.

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And by doing so we're actually creating a new column for our summary data frame.

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So the cap m return column A.B. F on the right hand side.

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The new column and we can actually compare the cap and return column with the actual return.

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And actually for our constituents of the market portfolio these are actually equal.

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So for Amazon we have uh 31 percent.

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Also here then for Boeing we have the same values then for the Microsoft stock.

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We have almost the same values then for the market portfolio of course we have also the same values

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and we can see for the three stocks that have zero weight and our optimal portfolio that the cap M returns

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are higher than the actual returns.

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So for the at this nice talk the cap m return is twelve point eight percent and the actual return is

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10.

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And we could say here that the Disney stock should have returned twelve point eight but it underperformed

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and only showed a 10 percent.

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And that's exactly the reason why there's zero weight in our optimal portfolio.

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And also here for the IBM stock.

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So the actual historical return is far below the cap m return and for Coca-Cola it's actually pretty

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close.

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And with this we are finished with our video and I hope to see also in the next one by.
