The seller of the shares, Uniper Ruhrgas International GmbH, will keep an 18.26% stake in the company.
The announcement doesn't disclose the sum of the deal.
LSM's Latvian-language service estimates that as the Marguerite fund has purchased 11.559 million shares the total value of the deal might be close to €115m based upon current prices trading on the OMX Rīga stock exchange.
The largest shareholder in the company is now Russian Gazprom, controlling 34% of the shares.
The Marguerite Fund owns 28.97%, followed by Uniper Ruhrgas International GmbH (18.26%), LLC Itera Latvija (16%) and othe minor shareholders (2.8%).
Marguerite is a fund investing in European infrastructure. It was established with support from six leading European financial institutions and the European Commission. A spokeswoman for the fund refused to comment on the deal when asked by LSM.
In 2014 Uniper - formerly EO.N Ruhrgas - announced it wants to sell its shares in the utility. The price offered was revealed to be €220m, which Prime Minister Laimdota Straujuma called 'too high'.
Latvijas Gaze is currently headed by former Prime Minister Aigars Kalvitis and has recently been trying to defend its 20-year monopoly of gas storage and distribution against efforts by the European Commission to make it open up to competition by 2017.
But with the European Commission now indirectly backing one of its major shareholders, fending off EU unbundling could become more problematic.
Latvijas Gaze's major asset is the massive Incukalns gas storage facility near Riga which supplies gas to Estonia, Lithuania and Russia as well as domestically.
However, Latvia remains almost entirely dependent upon gas supplies from Russia thanks to Latvijas Gaze's resistance to competition and the fact that those same Russian suppliers are among its shareholders.