Over the weekend a rather huge amount of sell orders built up at 270. It seemed to go from no orders at that level (and orders being processed at 269), to over 7 million at 270 within hours. How much of this was Supply Linden? Did you park a huge order at 270? Did you move an order that was previously at 267 or 265 to 270?
If you did, that was clearly the reason for the spike over the last couple of days. The market just can't work through such large orders.
If you truly want stability and not just as much extra cash for LL as you can justify, then you need to pick a target ceiling for the market, and put up a large sell order there and only there. And then announce it. Say it's 265. Put a huge order at 265 and announce that you are selling a virtually unending supply at 265. That will allow the content creators to fiddle around with sell orders in the 266-270 range. When the money supply truly is running so thin that there is some upward pressure, then the orders before 265 will dry up and Supply Linden will start selling/printing new money.*
If instead you are leap frogging over the orders of content creators in order to meet theorhetical projections of how much new money you expect to need (as I'm assuming you have been), you are really are creating instability, not stability.
* I can't remember whose idea this was. It was not mine, but the more I've thought about it, the more I prefer it to the current situation.