WSJ reports on the month over month change:
China remained the largest holder of U.S. Treasury securities, having surpassed Japan late last year. China increased its holdings to $801.5 billion in May. Japan, the second-largest holder of U.S. Treasurys, decreased its holdings to $677.2 billion.
Rachel Ziemba (via Brad Setser's Follow the Money) with the broader trend:
While the decrease in the US current account deficit means that the U.S. may be less reliant on foreign finance in 2009, the U.S. has become even more reliant on China as a share of its foreign finance. China has been the largest reported holder of U.S. treasuries for some months now. But as of May China now accounts for 20% of total outstanding foreign holdings and almost equals the combined holdings of Russia and Japan.Source: TIC
Since last fall, China dramatically scaled up its purchases of the shortest term, most liquid U.S. assets. It has purchased $196 billion in treasuries of less than 1 year maturity from July 2008 to May 2009. In part this might reflect a shift last fall within China’s US dollar portfolio. It also vastly decreased its holdings of US agency bonds, while slightly adding long-term treasuries.