ok
despite what the help file says my results were:

/window -alkCs @text
//loadbuf @text $sfile(*.log)

//echo -a $line(@text,$fline(@text,stock*,1,2),1) $fline(@text,stock*,1)
no line number

//echo -a $line(@text,$fline(@text,stock*,1,2),1) $fline(@text,stock*,1,1)
no line number

//echo -a $line(@text,$fline(@text,stock*,1,2),1) $fline(@text,stock*,1,2)
returns "27"

//echo -a $line(@text,$fline(@text,stock*,1,2),1) $fline(@text,stock*,1,3)
returns "27"

/me shrugs