Tariffs have shaken the markets - how worried should we be? The sharp fall in stock markets across the world shows no sign of letting up after the US imposition of sweeping and swingeing tariffs and many are asking does this qualify as a stock market "crash" and what that could mean for them? The word crash has been used sparingly over the decades and is usually reserved for a fall of over 20% from a recent peak in a day, or over the course of a couple of days. On 19 October, 1987 - also known as Black Monday - the US stock market lost 23% of its value in a single day, and other stock markets had similar falls. That was most definitely a crash. In 1929, the US stock market lost over 20% of its value in two days - and 50% within three weeks. That was the famous Wall Street Crash that ushered in the great depression of the 1930s. By comparison, the US stock market has lost around 17% of its value from its peak in February and is now down 2% from where it was this time last year. The UK FTSE index has fallen sharply though not by as much. This is partly because it closes earlier than New York, and so it often plays catch up with whatever happens in the US the next morning. Follow live updates Nevertheless, these are the biggest and quickest declines we have seen in world markets since they were gripped by the panic of Covid-19 in early 2020. A decline of 20% from a peak is considered a "bear market" - a description of a market that appears to be more likely to go down than go up. We are very close to that description right now.