How to pass a string containing slashes to sed without treating it as a file? (No such directory or file)

I need to pass a string containing slashes to sed to extract some values from it, but when I try to do so it treats it as a directory/file and throws a "No such directory or file" error instead. I'm assuming this is because it reads it as a path and tries to find the file when it is not the intended effect. Example: my_value="my/value" operand="$($my_value | sed -n -e 's/^\(.*\)\/.*/\1/p')" # Expected echo $operand : my Note: I am new to bash scripts so this could be the wrong way to go about this