Bitcoin traders seem to be taking Monday’s 11 percent slump — triggered by China ruling initial coin offeringsillegal — as a buying opportunity. The cryptocurrency is rising a second day, gaining back about 4.5 percent over that period as of 3:27 p.m. Hong Kong time, and Monday’s losses have barely made a dent in bitcoin’s 2017 surge, with the virtual currency still up 379 percent since January. China’s central bank ordered all fundraising related to ICOs halted immediately, the strongest regulatory pushback thus far to the swelling market for digital token sales.