After four straight years of pulling money out, foreign investors have invested $66.4 billion into the U.S. stock market through September, the “biggest buying spree since 2012,” according to a recent article in The Wall Street Journal (data from Deutsche Bank).

“And there are signs that foreigners aren’t done buying,” the article says, noting that a recent survey by Bank of America Merrill Lynch showed that allocations to U.S. equities by global fund managers rose in November. “Overseas investors,” it adds “could become an increasingly important factor for the U.S. stock market at a time when other drivers of the long rally have been fading away.” The interest, it explains, is being fueled by a positive growth outlook in the U.S. and corporate profitability, which could be further bolstered by tax reform measures.

That said, the article reports, lofty valuations are “making some foreign investors pause,” citing comments from Lloyds Banking Group chief investment officer Markus Stadlmann: “The U.S. market is very expensive and earnings expectations for next year are very, very optimistic.”