Rating's agency Moody's has downgraded 15 of the world's top banks, including three British banks, Barclays, RBS and HSBC. Lloyds also had its ratings cut by Moody's in a separate announcement.

Other banks to see their ratings cut include Citigroup, Goldman Sachs and Morgan Stanley. Four banks including RBS and HGSBC suffered a ratings cut by one notch on Moody's ranking scale. Barclays was one of ten banks to have their rating reduced by two notches. Credit Suisse was marked down by three notches.

Greg Bauer, Moody's global banking managing director, stated that banks' exposure to volatility in the world's financial markets was the reason for the downgrade.

You can't say they didn't see it coming. Moody's Investor Service launched a review of 17 of the world's biggest banks back in February. And on Thursday bank stocks fell ahead of the announcement, as it appears that banks had been forewarned of the downgrade.

It is now feared that the downgrade will make it harder for the banks to borrow money commercially.

Written and narrated by Alfred Joyner