(CNBC) Bitcoin prices have seen a strong rally this this week in the run-up to and following a U.S. Senate hearing on Monday, which has been interpreted favorably by traders, but the sheer size and speed of the rally has reignited fears of a bubble in the market.

On Tuesday, bitcoin prices touched a fresh record high of over $900 on the Mt. Gox exchange, a 6,445 percent increased on its value in January, when it traded at $13.75. However, it was a volatile morning that saw the currency plunge as low as $502.

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