HONG KONG — China’s financial system is in danger of becoming too big to bail out.

Official bank lending has more than doubled since the global financial crisis, growing nearly twice as fast as the overall economy. The even bigger problem, however, appears to come from the rise of a shadow banking system that has allowed a number of companies and individuals, often with political connections, to borrow from state-controlled banks at low interest rates and relend the money at much higher rates to private businesses desperate for credit at almost any price.

Now, in an effort to wean the banks and the economy off their addiction to such risky practices, Beijing has pledged to deliver what amounts to the country’s most sweeping financial overhaul in decades. Markets will play the “decisive” role in directing the economy, policy makers promised last month after a key plenum meeting of the Communist Party leadership. Interest rates are to be liberalized, cross-border investment will be welcomed and regional and bureaucratic protectionism will be curtailed, they declared.

But already, even relatively modest government moves are producing turbulence in money markets; just this week China’s central bank was forced to back off, at least temporarily, to avoid putting too much stress on the banking system and potentially drawing an angry reaction from powerful vested interests in China accustomed to paying very little for their loans.

“It’s been pretty clear since June, and especially clear since the plenum, that the new crowd is interested in tightening monetary policy and letting interest rates rise,” said Arthur R. Kroeber, the Beijing-based managing director of GK Dragonomics, an economic research firm. “The purpose is to reduce the rate at which credit is expanding, which has been a bit of a problem over the last couple of years.”