Blue: Because deep book info is very resource-intensive. Instead of a single level (quote\sale) showing bid/ask and size, there are 10 additional bid sizes and 10 additional ask sizes displayed. I've never really stopped to analyze it, but the sizes in the bids/asks away from the current inside quotes change a lot even if there is no trading taking place, so it probably much more than a 20:1 upscope in server processing load and internet bandwidth. I guess IB made a business decision to limit the number of deep book feeds they would provide for "free" based on an analysis of the cost to provide more feeds against estimated additional commission revenue. After years of customer complaining they finally started selling ($30/mo) additional Level 1 quotes in 100 quote blocks. There appears to be no similar offering for deep book data (or if there is it's well hidden or obscurely described). Jack
Is there some reason that a billion dollar tech co with dozens of programmers can't figure out how to stream their quarterly conf call with decent audio? Maybe its harder than it looks.