Accelerating interest in the interesting case of UK interest rates

As John reminds us in his blog A seven year emergency we have now seen the official Bank Rate at 0.5 per cent for the past seven years. Understandably many attribute the financial crisis that led to the easing of monetary policy to the lending practices of commercial banks. Consequently, it is important that we better understand (and monitor) banks’ behaviour. Some argue that these practices are affected by the macroeconomic environment, with credit conditions varying across the business cycle. We consider here what recent patterns in interest rates might tell us about credit conditions.

One way in the macroeconomic environment might affect commercial banks’ lending practices is through the difference between banks’ lending rates and the official Bank Rate. We can think of such interest rate differentials – or spreads – as a credit premium. In other words, the greater are commercial borrowing rates relative to the Bank Rate, the greater the credit premium being demanded by banks. On the other hand, the lower the interest rate on borrowing relative to the Bank Rate, the smaller the credit premium.

Some economists argue that interest-rate differentials will fall when the economy is doing well and increase when the economy is doing less well. This is because the probability of default by borrowers is seen as smaller when the macroeconomic environment improves. If this is the case, it will tend to amplify the business cycle, since economic shocks will have larger affects on economic activity.

Consider a positive demand-side shock, such as a rise in consumer confidence, which lowers the propensity of households to save. As the positive shock causes the economy’s aggregate demand to rise, the economy grows. This growth in economic activity might result in lower borrowing rates offered by commercial banks relative to the official Bank Rate. Since savings rates tend to be close to the official Bank Rate, this also means that the cost of borrowing falls relative to the interest rates on savings. This financial effect further stimulates the demand for credit and, as a consequence, aggregate demand and economic activity. It is an example of what economists called the financial accelerator.

Similarly, the financial accelerator means that negative shocks depress economic activity by more than would otherwise be the case. A fall in consumer confidence, for example, would cause economic activity to fall as aggregate demand weakens. This, in turn, causes banks to raise borrowing rates relative to the Bank Rate and savings rates. This further dampens economic activity.

The chart shows the Bank Rate along with the average unsecured borrowing rate on loans by Monetary Financial Institutions (MFIs) of £10 000. (Secured borrowing is that which is secured against property.) We use this borrowing rate to capture general trends in commercial borrowing rates.

As expected, we can see that the borrowing rate is greater than the Bank Rate. In other words, there is a positive interest-rate differential. However, this differential is seen to vary. It falls sharply in the period up to the financial crisis. In early 2002 it was running at 8 percentage points. By summer 2007 the differential had fallen to only 1.7 percentage points. (Click here to download a PowerPoint of the chart.)

The period from 2002 to 2007 was characterised by consistently robust growth. The UK economy grew over this period by about 2.7 per cent per annum. This would certainly fit with the story that economic growth may have contributed to an easing of credit conditions which, in turn, helped to induce growth. Regardless, the falling interest-rate differential points to credit conditions easing.

The story from 2008 changes very quickly as the interest-rate differential increases very sharply. In 2009, as the official Bank Rate was cut to 0.5 per cent, the unsecured borrowing rate climbed to close to 10.5 per cent. Consequently, the interest-rate differential rose to 10 percentage points. Inter-bank lending had dried up with banks concerned that banks would default on loans. The increase in interest rates on lending to the non-bank private sector was stark and evidence of a credit market disruption.

The interest-rate differential has steadily declined since its peak at the end of 2009 as the unsecured borrowing rate has fallen. Hence credit conditions have eased. In fact, in February 2016 our indicative interest rate differential stood at 3.8 percentage points, unchanged from its level in January. This is its lowest level since July 2008. Furthermore, today’s differential is lower than the 6.5 percentage point average over the period from 1997 to 2003, before the differential then went on its pre-crisis fall.

Given concerns about the impact of credit cycles on the macroeconomy we can expect the authorities to keep a very keen eye on credit conditions in the months ahead.


Bank holds UK interest rates at 0.5% BBC News (17/3/16)
UK’s record low interest rates to continue in 2016 The Guardian, Katie Allen (3/3/16)
Big rise in consumer credit in January BBC News, Brian Milligan (29/2/16)
Household debt binge has no end in sight, says OBR The Telegraph, Szu Ping Chan (17/3/16)


Bankstats (Monetary and Financial Statistics) – Latest Tables Bank of England
Statistical Interactive Database – interest and exchange rates data Bank of England


  1. Why would we expect banks’ borrowing rates to be higher than the official Bank Rate?
  2. What factors might lead to a change in the interest-rate differential between banks’ borrowing rates and the official Bank Rate?
  3. How would we expect a credit market disruption to affect the interest-rate differential?
  4. Explain how the financial accelerator affects the change in the size of the economy following a positive demand shock.
  5. Explain how the financial accelerator affects the change in the size of the economy following a negative demand shock.
  6. What is the impact of the financial accelerator of the amplitude of the business cycle?
  7. How might banks’ credit criteria change as the macroeconomic environment changes?
  8. How might regulators intervene to minimise the effect of the financial accelerator?