'portfolio-based' is a compound of 'portfolio' and 'based'. 'portfolio' originates from Italian, specifically the word 'portafoglio', where 'portare' meant 'to carry' and 'foglio' meant 'sheet' (leaf). 'based' is the past-participle/adjectival form of 'base', ultimately from Latin/Greek roots.

'portfolio' entered English via Italian 'portafoglio' (literally a case for carrying sheets) and earlier Latin 'portare' + 'folium'; 'base' comes from Latin/Greek 'basis' via Old French, becoming the English verb/adjective 'base'/'based'. The compound 'portfolio-based' arose in modern English to describe things founded on or using a portfolio.

Initially, 'portfolio' referred to a physical case for papers and 'base' referred to a foundation; over time 'portfolio' broadened to mean a collection of works or assets, and 'portfolio-based' came to mean 'having its foundation or method in such a collection'.