Unfortunately, your method 1 isn't going to do the trick because the regex is going to consume %/%/ when doing the first match and the next attempted match is left with ISIN/US1252691001 to work with so the match fails.

$ perl -le '
> $string = q{%/%/ISIN/US1252691001};
> @matches = $string =~ m{/(.*?)/}g;
> print for @matches;'
%
$
[download]

Cheers,

JohnGG