https://exchange.coinport.com/coin/BTC
Bitstamp, Bitfinex, Huobi, Okcoin, etc. nine tenths of the coins on their books could be fake and using them when there's the possibility of that is irresponsible and asking to get Goxed. They've no excuse for it, what do they have to hide? Exchanges have evolved beyond that and its up to users to demand transparency or take their business elsewhere.
+1
As far as other exchanges at this time the market is being manipulated as a group that has colluded and are working to lower BTC/USD and raise LTC/BTC up by artificially inflating the LTC/USD .
they also use alts that are supported by the exchanges where they have chose.
I have the details on my recent history. However I will link to it here.
https://bitcointalksearch.org/topic/m.10299896
Edit: Also forgot to mention that exchanges that offer leverage trades also have an algorithm that prevents market calls from hitting the orderbook untill there is more buildup of bids.
Stop trading with leverage.
Bitfinex is running an algorithm to handle the margin calls. The algorithm starts selling but limits itself to a 10% drop in prices within 1 minute. If prices drop more than 10% in 1 minute it will stop selling and wait for buy orders to come in. Once there are again a certain amount of buy orders in the orderbook the algorithm starts selling again until all margin calls are met.
Edit: LeMogawai was the first to point this out in this post and it matches my personal observation at the time of the event.
This seems to be an interesting way to deal with cascading margin calls but can also be considered as borderline market manipulation from the exchange side. By spreading out the sell orders over time the downwards momentum is reduced, however traders end up trading against the exchange itself and not the market anymore. The exchange has an informational advantage at that point and is therefore more likely to profit than the traders. Fortunately, this only lasted for about 10 minutes after which control was given back to the market.