China's factory activity likely shrank for a ninth month in December, as policymakers grapple with lagging domestic demand and sliding factory profits along with volatile trade relations with key export markets. The official purchasing managers' index (PMI), a sentiment-based survey, is expected to remain at 49.2 in December, unchanged from the previous month and below the 50-point threshold that separates growth from contraction, according to 20 economists polled by Reuters. The data is due on Wednesday.