Short-term capital asset defined as held not more than twelve months; liquidation periods excluded and prior-owner holding included. A new clause defines short term capital asset as a capital asset held by an assessee for not more than twelve months immediately preceding its transfer. The explanation excludes post liquidation periods for shares in a company in liquidation, includes the period the asset was held by a prior owner where transfer rules apply, and provides that holding periods for other assets shall be determined by rules the Board may make.