20,000 coins using 3x leverage... Need something like 6667BTC to borrow the remainder. So you could flash that wall with 6667BTC + whatever to cover borrowing costs, or ~1.6MM.
It's entirely possible, and I'm not sure that it's been discussed to any length, that the bid (and ask?) wall(s) are predominantly borrowed money.
We would see increase/reduce is swaps... or?
I don't trade leverage, so I can't comment with certainty. But I believe that bfxdata.com only shows that swaps were taken, not that they were actually used in any capacity. So if I had 1.6MM+ I could borrow the remaining funds, but not actually place a limit or market order. I could borrow every single coin there is to borrow (as long as I can pay the interest) but not actually sell them. Effectively bfxdata would show that those funds had been lent out, but we wouldn't know that they were used until we could correlate the swap against buys/sells.
If someone knows otherwise, hopefully they can speak up.