25. Cash and cash equivalents – excluding bank overdrafts
(a) Analysis by nature
| 2022 US$m | 2021 US$m | |
| Cash at bank and in hand | 104 | 113 |
| Short-term investments | 75 | 67 |
| 179 | 180 |
The effective interest rate for cash and cash equivalents held at 31 March 2022 is 1.2% (2021: 0.8%). There is no material difference between the fair value and the book value stated above.
(b) Analysis by external credit rating
| 2022 US$m | 2021 US$m | |
| Counterparty holding of more than US$2m: | ||
| A rated | 130 | 83 |
| B rated | 22 | 79 |
| Counterparty holding of more than US$2m | 152 | 162 |
| Counterparty holding of less than US$2m | 27 | 18 |
| 179 | 180 |