The sportsbooks of Las Vegas perform a daily juggling routine that commences when they open for business and concludes each night when they close up shop. This act means that the sportsbook director must make decisions concerning how to move the betting lines, juggle the money, and not leave the book exposed to precarious positions.

The booking strategies are changing and part of these changes involves the creation of a fluid money line on the numbers themselves. For example, if the Green Bay Packers are —3 over the Denver Broncos, with 3 such a key number in NFL football games, there is a universal reluctance to move off that number.

One way to get around this is to make the number —3 -120. This means that if you want to bet on Green Bay, you are laying three points (Green Bay must win by 4 or more for you to win your bet), plus you are laying $120 instead of $110 for every $100 you want to win.

If more money comes in on Green Bay, the sportsbook director might move the number to —3 -125 and higher. When the money on a number moves to —140 or more, it is a signal to the betting world that this book doesn’t want any more action on that side, and is making it so expensive to bet on, that no one who bets on an everyday basis will go for it.

This strategy of moving the money and not the number helps prevent the books from getting "middled" (please refer to that section), and is being employed more and more for all types of bets in all sports.