From Traderpedia

All of the different investments owned by the same individual or organization.

A portfolio, at its most basic level, is a collection of investment or trading positions. Most people when thinking of portfolios do so in terms of stocks. That is not the limit to the discussion, however. They can include any number of finanicial instruments in all sorts of combinations.

Some portfolios are consciously created in a specific manner. Others are just the result of buy/sell activity.

See also portfolio management.