The Level I area of the Level II window provides 17 different data fields:
- Symbol Field: Symbol currently being displayed
- Short Arrow: Reflects Tick rule and Bid Test rule¹
- Last: Price of last trade
- Change: Change from previous days close
- Volume: Total daily volume
- High: Highest price of the day
- Low: Lowest price of the day
- Open: Market opening price
- Last Trade: Time of last Trade
- Bid: Current bid (left side of the Level II)
- Ask: Current ask (right side of the Level II)
- Close: Closing price of the previous trading day
- Last Vol: Volume of the last trade
- Size: Available shares (inside market) bid
- Size: Available shares (inside market) ask
- Spread: The difference between the inside bid and ask
- Mkt: The market associated with the symbol

Securities trading from other exchanges will follow the Plus Tick rule. The arrow will point up and turn green when the price of the last trade was either equal to the last uptick or was higher than the price of the last trade. The arrow will point down and turn red when the price of the last trade was either equal to the last downtick or was lower than the price of the last trade. Refer to SEC Rule 10-a-1, Plus-Tick Rule.