The shares not taken up by shareholders in a rights issue. Shares may not be taken up either because the shareholder chooses not to (the so-called lazy shareholder) or because the shareholder cannot, for example if it was excluded from the offer because of overseas securities laws. The rump may also include shares representing aggregated fractional entitlements.

Where the rights issue is being underwritten, the underwriters will seek subscribers for the rump in the market and will take up any remaining shares (known as the stick) themselves.

For further details, see Practice notes, Rights issues: overview and Underwriting agreement: rights issue: guide to key provisions and negotiation: Underwriting obligations.