CML and market portfolio having, market, reading, efficient

atate2007

Hi Guys,

I'm reading the "Asset Pricing Models" section for level 1.

I'm understanding how having a risk free asset with a portfolio M transform the efficient frontier to the CML.

What I'm not understanding, is the raisonning that says: since this is true for all investors, portfolio M must be the market portfolio

Tks for your help