With the help of the Internet, Yu'ebao was able to become China's largest single fund in relatively short order. By the end of March, Yu'ebao reportedly held some 541 billion yuan ($86.6 billion) in funds under management.

The wild popularity of Yu'ebao and other related funds lies not in the fact that they resolve fundraising bottlenecks that have long hampered growth in the real economy. They have been a hit because they offer yields that beat those found with traditional bank savings accounts.

But weren't banks under strain before the spread of Yu'ebao? Last June, interbank lending rates spiked to some 13 percent. According to the recently issued China Financial Stability Report 2014, interbank liabilities grew from 5.32 trillion yuan ($850 billion) in early 2009 to 17.87 trillion yuan by the end of 2013. Meanwhile, loans and deposits have grown at far slower rates over the same period, a disparity which exposed the cracks in traditional banks last summer when authorities temporarily turned off the liquidity tap.

The author is Ye Tan, a commentator.