IOU

Governments sell bonds - essentially an IOU - to raise money for public spending and in return they pay interest.

The government sell bonds - essentially an IOU - to raise money from financial markets and these are viewed as a safe investment, meaning the US normally does not need to offer high rates to attract buyers.

Investors see US Treasury securities as one of the safest possible bets, because the bonds - which are kind of like an IOU - are backed by the US government.

A bond is a bit like an IOU that can be traded in the financial markets.

While that may be technically correct, the £1.68bn value is based on an IOU that is ultimately backed up by Severn Trent Water itself.