Market makers are those participants which ensure the tradability (market liquidity) of securities by providing continuous bid and ask prices.
Market Surveillance
Market Surveillance ensures that orders are correctly executed, monitors the proper course of exchange trading, and investigates any suspicion of legal violations.
Maturity
On the maturity date, repayment is made for a certificate or warrant. This can take place in the form of a cash settlement or the physical delivery of the underlying instruments.