The public is getting nervous about reports on investments in U.S. companies by sovereign-wealth funds--pools of overseas government-controlled money. Middle Eastern and Asian countries have made headlines by taking stakes in U.S. financial companies such as Merrill Lynch & Co. and Citigroup -- and Americans don’t like it. A survey by Public Strategies Inc. shows that, while U.S. citizens don’t really know much about the funds, they oppose their investments in U.S. companies because they fear that it hurts the U.S. economy and jeopardizes national security.

The funds’ stakes are below the limit that sets off alarm bells by the federal government and companies are carefully structuring such investments to make sure that the funds have no more voting privileges than other large shareholders. For example, in regard to Nasdaq Stock Market Inc.’s deal to acquire another exchange operator, OMX AB, CEO Robert Greifeld told The Wall Street Journal that they’ll work with investor Bourse Dubai the same way they work with private-equity funds. But some politicians, sensing public fears, are raising the subject of investments by foreign governments in speeches and may try to seek restrictions on sovereign-wealth fund activities.

The U.S. Treasury is leading a charge toward establishing rules to govern the activities of sovereign-wealth funds and the International Monetary Fund (IMF) is working on a voluntary code of best practices that would deal with how funds are structured, governed and how they disclose information about their investments. But many sensitive issues are beyond the purview of the IMF. Whether the rules that evolve are requirements or voluntary remains a question for the U.S. and all other nations that receive investments from the funds.