The assessment is based on strong, corroborating evidence from the provided sources. A reputable news outlet (MSN) directly states that European investors own $10.4 trillion in U.S. stocks. Crucially, another source identifies the U.S. Treasury as the definitive primary authority for this specific type of data ('U.S International Portfolio Investment Statistics'). It is highly probable that the news report is citing data originating from this official government source. While several other low-authority sources also repeat the claim, they are less critical to the assessment than the combination of the reputable secondary source and the identified primary authority. The remaining high-authority sources are not relevant enough to either confirm or deny the specific figure, and there is no conflicting evidence presented across any of the sources. This strong alignment between a credible secondary source and the identified primary data authority makes the statement very likely to be true.