After years of splurging on pricey condos and mansions in the West, Asia's rich now are buying small office buildings, retail shops and branded hotels in Europe and North America, searching for stable returns and diversifying away from home markets they view as increasingly risky and volatile.

In the first six months of this year, Asian private investors poured $1.9 billion into U.S. commercial properties, according to data from Real Capital Analytics. That total already dwarfs the $551.4 million worth of U.S. commercial real estate purchased by Asian private investors in 2012.

Trophy assets still draw attention, including such deals as Chinese developer Zhang Xin's acquisition of a minority stake in the General Motors Building in New York in June. But real-estate insiders around the world say they are seeing a surge of interest by less-wealthy Asians for deals worth less than $30 million, which are typically the domain of local, private investors.

Real Capital added that its figures are likely underreporting the trend, since the firm doesn't track transactions below the $2.5 million mark. Moreover, the firm can't account for investments foreign investors made through a local partner and through third-party entities such as an unlisted real-estate-investment trust. As well, the firm admitted it doesn't capture all the flows into the U.S. via the popular EB-5 investor-immigration program, which grants five-year visas to those who invest as little as $500,000 in a business