In a recent report, the firm tracking the market cryptocurrencies Coin Metric pointed out that the majority of the trading volume in the pair bitcoin – dollar in exchange houses in the united States, moves through four companies.The study, published this week, assessed how it is distributed the trading volume of bitcoin between the houses of change, based on data from the first of April, 2019 until the date of publication, the 10 of September of this year. According to analysts, the concentration of trade in a single currency exchange house can pose risks to the market if it fails, as happened in the past with Mt Gox. In that case, the house of change concentrated 70% of the trade of bitcoin.The evaluation was made based on the trading volumes of bitcoin against the u.s. dollar in nine exchange houses in the united States. The results reveal that the majority of the operations are concentrated in Coinbase, Bitfinex, Bitstamp, and Kraken. These four companies handle 85% of the total volume of the markets evaluated.Coinbase, the exchange house with the highest total trading volume in the north american country, showed figures of up to 32% of the total trade of bitcoins against us dollars in the period under review. In addition, the report points out that the house of change increased in 8% of its operations in that market, to the detriment of Bitfinex, whose share fell from 25% to 19%. This loss of the market volume of Bitfinex has its explanation in the recent legal problems faced in the united States.Source: Coin MetricEn the period studied, the average volume of exchange of bitcoin for an hour, through Coinbase, ranges between 300 BTC and 2,000 BTC. According to the report, the rest of the houses of change assessed for the study, including Gemini, itBit and Bittrex have volumes less than 10%, an amount quite lower than that shown by Coinbase.The analysts of Coin Metric provided that, due to regulatory pressures force, Coinbase could concentrate even more of the market BTC – USD, “as more and more houses change to limit the access of the traders based in the united states. UU.”. This would imply a risk concentration of the trade of bitcoin, as mentioned previously.It is worth remembering that the asian Binance, the greater house of change criptomoneda to criptomoneda by volume traded, announced in June of this year that he would no longer serve the u.s. market through its main platform, Binance.com. The company was forced to create a new platform that will be compliant with the regulations of the united States, to cater to the users of that country.