Outline
       •  Fundamentals of stock market trading 
       •  High frequency trading and its effect on the stock market
       •  Stock market synchronization requirements
       •  (including some history)
       •  How a NIST disciplined clock works
       •  NIST disciplined clock performance
       •  Monitoring the time on NTP/PTP servers
       •  Summary
   Fundamentals of stock market trading
      Fundamentals of Stock Market Trading 
                                  - I
                    The bid and the ask
     Every stock has a “bid” and an “ask” price. 
         Buyers of a stock pay the “ask” price
         Sellers of a stock receive the “bid” price
         All stock traders know that you buy at the “ask” and sell at the 
          “bid”
      Fundamentals of Stock Market Trading 
                                          - II
                                 The spread
      The difference between the bid and the ask is the “spread,”  or the profit 
         made by the market maker who handles the transaction. 
      For example, let’s say stock ABC has a bid of $20.25 and an ask of $20.26.  The 
         market maker buys shares from me at $20.25 and sells them to you at $20.26, thus 
         making a profit of 1 cent per share on the transaction.
            When an investor sells, a market maker buys, and when an investor buys, a market maker 
             sells.  Thus, market makers do the opposite of what investors do; they buy at the “bid” and 
             sell at the “ask” 
      Fundamentals of Stock Market Trading 
                                        - III
               Decimalization of the spread
       For many years, stocks traded in fractional dollars.  The tick price was the minimum 
         amount that the stock price could change.  It was once ¼ (25 cents) then reduced to 
         1/8 (12.5 cents) in 1997, and finally to 1 cent in 2001, when the New York Stock 
         Exchange started trading in decimal stock prices.  This made spreads get smaller.  For 
         example:
             Bid is 21 ¼, ask is 21 ½, spread is 25 cents (prior to 1997)
             Bid is 21 ¼ , ask is 21 3/8, spread is 12.5 cents (1997 to 2001)
             Bid is 21.25, ask is 21.26, spread is 1 cent (after 2001)