this hike didn't even increase the amount of active swaps at all.
Actually it did, total sum of active usd swaps showed an increased of ~1 million USD (from 16 million to 17 million) just after the interest peak at 17:47UTC. It lasted less than an hour and total sum of USD swaps declined back to 16 million at 20:00UTC.
there is no market activity to explain the suck up of so much liquidity in the slightest. Bitcoin trading is nearly dead at the moment volume wise
You're right about the trading volume indeed, I checked the trade volume from 17:47 UTC to 21:00 UTC. There was way to little trading volume to explain the 1 million swap as a long BTC / LTC position.
Roughly 110 BTC on Bitfinex in that period were bought and sold, roughly 250 BTC on Bitstamp and roughly 450 LTC on bitfinex. So in total (360BTC * $450 = $162000 and 450LTC * $10.6 = 4770) $166770 worth of trades were done in the hours after the interest spike.
To me it all seems very similar to the reddit quote I posted on may 14 in this thread. I'm not saying that someone is (or someones are) doing anything illegal or anything but it does seem to me someone is trying to manipulate the swap rates. Just my two pennies...
check the first two charts at
http://www.bfxdata.com/bitfinexLiquidityUSD.php (or the tables below) if you want to verify my claims.