The two ICSDs
Eurobonds are held and settled through two international central securities depositories (ICSDs): Euroclear Bank in Brussels and Clearstream Banking in Luxembourg. A connection between them, known as "the Bridge", allows trades between their participants.
Global notes
Historically Eurobonds were bearer certificates with coupons that were physically clipped and presented for payment. Today a bond is normally represented by a single global note held by a common depositary or common safekeeper for the ICSDs. Investors own an interest in it through accounts at banks and brokers.
ISIN codes
Each bond has a 12-character International Securities Identification Number. Bonds issued through the ICSDs typically start with "XS"; bonds issued in a domestic market start with that country's code, such as "US", "DE" or "GB".
Settlement cycle
Secondary-market Eurobond trades usually settle two business days after the trade date (T+2), on a delivery-versus-payment basis so that the cash and the bonds move at the same time. New issues settle on the closing date set in the deal, often five business days or more after pricing.
The chain of custody
A private investor rarely deals with Euroclear or Clearstream directly. Ownership runs through a chain: the ICSD → a participant bank → possibly a sub-custodian → the investor's bank or broker. Understanding who holds your assets and how they are segregated is an important part of due diligence.