Initial target string:

string = "The Euro STOXX 600 index, which tracks all stock markets across Europe including the FTSE, fell by 11.48% – the worst day since it launched in 1998. The panic selling prompted by the coronavirus has wiped £2.7tn off the value of STOXX 600 shares since its all-time peak on 19 February."

Source: https://www.theguardian.com/

Example:

>>> import re
>>> s = r"\d{4}"
>>> t = re.compile(s)
>>> result = re.findall(t, string)