WordNet records no synonym and no antonym for portfolio. It is the only member of each of its synsets, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
a large, flat, thin case for carrying loose papers or drawings or maps; usually leather
“he remembered her because she was carrying a large portfolio”
a set of pieces of creative work collected to be shown to potential customers or employers
“the artist had put together a portfolio of his work”
Synonyms, antonyms and the broader and narrower relations for portfolio come from Princeton University’s WordNet. Full sources and licences.
a list of the financial assets held by an individual or a bank or other financial institution
“they were disappointed by the poor returns on their stock portfolio”
the role of the head of a government department
“he holds the portfolio for foreign affairs”