I think I know the answer but I'm curious if I'm correct.

There are a lot of very knowledgeable people on here when it comes to set-up's, pricing, marketing etc.

Do the online agencies check flights and routes that they think there will be a future demand for (that they can make money on) and when flights become available and/or perhaps drop in price, do they do a block/group booking for x-number of seats (say 10-20 on a flight) and I know that some airlines allow you to submit the names of people travelling as late as 24-hours before flying to the airlines (as a privilege of a group booking compared to a normal booking submitting the names when booking and paying)? which then means they have a block of seats reserved on a service and they can re-sell them on in the future for profit (I've noticed that the formula tends to be somewhere in between when the tickets were at their cheapest and a discount on what they are at any given time going forward - maybe stating the obvious there).

Maybe I've answered all my own questions and maybe it's obvious - but I'd just like to know - especially if I've got it wrong and it's done another way?