Jeff Gundlach has a theory on why bitcoin is surging

Jeffrey Gundlach ‏, CEO of DoubleLine Capital, said Tuesday there could be a connection between bitcoin prices and the decline in Chinese stocks.

In a Tuesday afternoon tweet, Gundlach noted that bitcoin has doubled in less than 2 months, while the Shanghai composite has fallen "almost 10%" over the same time period. In contrast, most major indexes have climbed so far this year — the MSCI World Index is up nearly 8.8 percent.

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The theory is the Chinese search for safe investments outside the country when asset prices fall sends buyers into bitcoin . The Chinese yuan's weakness in the last two years has also contributed to capital flight.

However, now more than just Chinese investors are driving bitcoin's price. Gundlach isn't wrong — there's just more to the story now.

"I think it is part of the equation but not the entire reason for the move in bitcoin," Brian Kelly, CEO of BKCM, told CNBC in an email. He pointed to increased demand from trade denominated in the Japanese yen and the U.S. dollar.

Trade in the Japanese yen has taken a greater share of volume, sometimes about half, as local authorities recognized bitcoin as a legal form of pay.

Meanwhile, Chinese demand shrank drastically this January when the People's Bank of China began investigating local bitcoin exchanges.

China's share of global bitcoin trade volume, as measured by trade in yuan, has fallen from a roughly 80 to 95 percent share to 10 percent or less since January, according to CryptoCompare.

Six-month bitcoin trade volume by currency

Source: CryptoCompare

The Shanghai composite has also fallen this year under pressure from increased Chinese regulation. The index is also not quite down 10 percent over the last two months — the composite has fallen 5.65 percent between March 22 and Tuesday, in local currency terms.

Bitcoin has more than doubled from $1,037.44 on March 22 to rise 120 percent to a fresh record of $2,291.09 on Tuesday.