Or go further and be like John Lewis (and Waitrose,owned by John Lewis) which makes every employee a partner. Then they get a share of all the profits as an annual bonus, as well as being owners.
Siemens employees can only own a very small number and value of shares individually; just think how many employees they have got; so its not obvious that they'll work harder because of it. The real value is in the psychological one of feeling that they are part of the company and have a part in it well-being instead of thinking of 'them and us' about it