question for institutional day/short term traders

How do you quantify your risk or does some one else do it for you? If so what do they use?

You can use stop loss orders to quantify the amount you're risking in a rough sense (and then this can get more precise when you factor in your likely slippage if using a market order).

For macro-level risk management you can set some limits on the maximum position sizes traders are allowed to take on, as well as a maximum amount they are allowed to lose per day.