Level II is a thinkorswim gadget that displays best ask and bid prices for each of the exchanges making markets in stocks, options, and futures. It is essentially a real-time ordered list of best bids and asks of an underlying that allows instant order placement. Like all other gadgets, Level II can be displayed as a section of the left sidebar or a separate window (see the Left Sidebar article for details).
In the gadget header you will see the following elements: the symbol selector, the 'clip' icon , the full name of the symbol, the current market price of the selected symbol, and its percentage and absolute change since midnight. The clip icon brings up a color-and-number selection menu; choosing a color in this menu will link Level II to all thinkorswim components with similar color. Consider linking Level II to a watch list so that clicking through the latter will immediately display the corresponding symbols in Level II.
For stocks and options, Level II is a color-coded display of best bid and ask prices from a given set of exchanges. Use the toggle in the upper right corner of the working area to switch between the pre-defined sets (books): Level II, NASDAQ Full Book, and BATS/EDGE Full Book. For futures, since they each trade on a single exchange, Level II displays first several layers of that exchange's book.
When you specify the symbol in the symbol selector, you will see the real-time quotes in the working area. The working area is divided into two sets of columns: bid-related (to the left) and ask-related (to the right). These columns identify the marketplace or market maker at the given bid or ask price with respective number of shares to be bought or sold (ask/bid size). In both ask and bid size columns, the numbers represent hundreds of available shares or contracts: for example, 3 in the bid size column means that there are 300 shares or contracts ready to be bought at the respective bid price at the respective exchange.
Since the purpose of Level II is providing you with best bid ask prices, the columns are sorted accordingly. By default, the bid area of the gadget is sorted in descending order by the bid price column, so that highest prices are on top. As it might be expected, the ask side is sorted vice versa: the default sorting displays lowest prices on top. You can re-sort the columns in the reverse order by clicking on the Bid or Ask title, or sort the set by exchange name or bid/ask price by clicking the title of respective column.
Level II enables you to add orders instantly. Click on a bid price in Level II to add a sell order; clicking on an ask price will prompt you to add a buy order.