During the height of the price rally yesterday, Bitcoin exchange Gemini which is managed by the Winklevoss twins, saw nearly $30 million in trading volume.
At their peak yesterday, Gemini processed a total of $28.19 million USD in bitcoin buys and sells. Total BTC transacted was 21,110.90 (which at the time market value was $1334.40 per bitcoin).
As you can see in the chart below, volume doubled April 27 and then on April 28, volume nearly doubled again. To replicate the chart, just remove the other exchanges in the chart to only show Gemini (in purple).
This chart below shows the price point on the Gemini exchange when the volume peaked yesterday.
Other exchanges too saw higher volume than normal, such as GDAX and OKCoin.
All volume across exchanges as subsided since then, going back to normalized trading volume. At the time of this writing, GDAX is currently trading the most bitcoin holding 23.42% of the Bitcoin exchange market share.