Did the price actually go up pre-fork because some thought they would get a new coin out of this? That would explain why price is going down now(no new coin), I mean the fork was a success so price should be rising.
Looking at the ETH/EUR rates, actually ETH dipped before the fork at about ~270 EUR per coin.
So it seems pretty stable now, going back and forth between 280 and 290 EUR per coin.