The description of a trading security includes both debt and marketable equity securities bought and held primarily to be sold in the near term. Trading activities typically involve active and frequent buying and selling to generate profits on short-term movements in market prices or spreads. ASC 320 does not specify how long securities in this category can be held, because the length of time will vary between investors and the nature of the securities. The phrases “selling them in the near term” and “held for only a short period of time” in the description of trading securities contemplate a holding.