Buy, sell or hold? I think it is too late to sell. The question in my mind is whether to “catch a falling knife” or wait until there is some confirmation of a bottom in technical or fundamental terms. (seekingalpha.com)

The phrase perfectly captures the dangers of buying into a declining market. To do so is like trying to catch a falling knife: the momentum is all down, and we all know what happens to those who grasp a razor-sharp blade in mid-air. (Charles Hugh Smith)

Bargain-hunters tempted by the banks' falling share prices should beware the Square Mile adage; it's dangerous to catch a falling knife. (Telegraph.co.uk)