$string =<<'TEXT';
<tr>1 The last company to fail was ISTF with losses of  $60M.</tr>
<tr>2 The last company to fail was ITF  with losses of  $60M.</tr>
<tr>3 The last company to fail wasISTF with losses of  $60M.</tr>
< tr>4 The last company to fail was ISTF 
with losses of  $60M.</tr >
TEXT

print "Found $1\n" while $string =~ m|<\s*tr\s*>([^<]*\bISTF\b[^<]*)<\s*/tr\s*>|gi;