the extra 100 TH1 had not been added yet - still waiting for next dividend to get mined. Bitfinex has always announced supply increases prospectively in this fashion.
That's really not enough time. Since most swap contracts are 30 days we should have 30 days notice before a change in supply. Otherwise we don't really know what we're buying or selling. It's now become a matter of speculating on whether or not bitfinex will intercede on the market, and when.
The supply should have no impact in the price - the price should reflect the net present value of the expected dividends. Increasing the supply doesn't change that. The only purpose of the announcement it to put a time certain for when the hashing provider is supposed to accrue an additional dividend for remittance back to Bitfinex.
We would strongly caution anyone from continuing to be long TH1 unless you believe that the dividends that you will receive through Dec 15 is more than the current bid price. For that to be true, BTW, difficulty would have to *drop* 10% every 2 weeks until Dec 15 - so - stay long at your own risk and remember that this is a BETA PRODUCT and Bitfinex will do what it needs to to keep the market rationally priced. This product is intended as a way to speculate on future difficulty. Substantial distortions and manipulations will not be tolerated.
Can you point to a single day since they've started where the market was rationally priced? The supply impacts the price because there was a shortage of swap contracts being offered. If your swap times out then you have to either renew (and swap rates increased in anticipation, and there aren't enough of them for everyone) or buy in order to close your position. As long as the supply of btc is massively higher than the supply of TH1 the market is ripe for manipulation.
When we get to the last 30 days before the contracts expire then every swap contract that lasts until after the expiration date will be taken regardless of their rate because they will never have to be paid back - it's just free money. So let's say no one offers swap past expiration (why would they?). That means everyone who has a short position will have to close it before the last day. That means they need to buy, which means someone will have to want to sell. That leaves shorters bent over a barrel begging someone with a contract to sell it to them to let them out. What will bitfinex do then, just give it to them?