Hillary Clinton’s family foundation quietly updated its list of donors last week, significantly reducing the amount that it says has been given by a Mexican telecom tycoon whose company was recently accused of deceptive U.S. advertising.

The little-noticed update to the website of the Bill, Hillary, and Chelsea Clinton Foundation added contributions made in the first half of this year. But it also dramatically reduced listed contributions from billionaire Carlos Slim.

Prior to the update, Slim was listed as a $1 million to $5 million contributor. The updated version of the site says he has donated between $250,000 and $500,000.

A spokesman for the group declined to speak on the record about the change, but a foundation official who asked to remain anonymous acknowledged the change. "If needed, we correct the attribution on our list to accurately reflect the source of the support," the official said.

The Clinton Foundation voluntarily discloses its donors, but the lack of any legal disclosure requirement makes it difficult to know whether its publicly available list of contributors is accurate and complete.

Slim, the world’s second-wealthiest man, runs a number of telecommunications companies in his native Mexico. One of them, TracFone, is a prominent U.S. federal government contractor. The company paid $40 million to the Federal Trade Commission in January to settle allegations of deceptive advertising practices.

TracFone has donated between $5 million and $10 million to the Clinton Foundation, according to its website.

Another Slim company, Inmobiliaria Carso, appeared on the Clinton Foundation’s donor lists for the first time this year. The company contributed between $1 million and $5 million, according to the foundation’s website.

A charitable group associated with Slim’s Telmex, which controls most of Mexico’s landline phone market, has donated another $1 million to $5 million, including contributions in 2015 (the dates of its contributions, and the extent of its support this year, are not known).

The foundation appears to have used the update to its website to correct other discrepancies in its donor rolls.

Clinton supporter Ira Lessfield was listed last year as a $250,000 to $500,000 donor. His Leesfield Foundation was listed as having given just $1,000 to $5,000. However, the latter’s tax filings revealed it has given at least $200,000 to the Clinton Foundation.

The updated donor list merges the two, putting "Ira H. Leesfield and Leesfield Family Charitable Foundation, Inc." in the $250,000 to $500,000 category.

The website appears to have corrected a similar discrepancy with respect to Fred Eychaner, combining the Chicago media mogul’s personal and foundation giving into one line item.

Unlike the Eychaner and Lessfield updates, however, Slim’s revised contribution numbers reveal a new vehicle for his donations to the foundation in Inmobiliaria Carso, which had not previously appeared on the foundation’s donor list.

The company’s donations are also of note given controversy over ties between the foundation and the New York Times. Inmobiliaria Carso is the investment vehicle through which Slim owns his sizable stake in the New York Times Company, according to publicly available financial statements.

Slim did not respond to a request for comment made through his personal website.