Chinese banks had more than 26 trillion yuan ($3.8 trillion) of wealth-management products held off their balance sheets at the end of December, a 30 percent increase from a year earlier, according to the central bank.The expansion of this form of shadow banking, with money eventually being diverted to quasi-loans and bonds, outpaced the 10 percent growth for normal lending during the same period, raising risks for the broader economy and undermining the country’s “deleveraging” efforts, the People’s Bank of China said Friday in its quarterly monetary policy report.