Recently I decided that I should confirm that the colors on L2 mean what I thought they did so I wrote Alphatrade and asked them what they meant, here's the response.
Dear Mr. Mueller,
The different colours are used to group together the different market makers by price. This is meant to make it easy to visually assess the strength, or depth, of the market on each side. Yellow would be the best inside bid or ask, with green, orange, blue and red representing the next best price. This is combined with the colour bands along the top to help you visually assess the market at a glance.
Please let us know if you have any further questions. Thanks!
AlphaTrade Support
Any input appreciated, now I'm confused!
muel <ggg>