Franklin Templeton Investment Management has upped its stake in Tennent's owner C&C Group to more than 6%.
A stock market notification yesterday showed Franklin purchased more than 3.4 million shares earlier this week.
That took its holding in Dublin-based C&C, which also owns cider brands such as Magners and Bulmers, to in excess of 20.96 million shares.
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The exact price Franklin paid for the stock it bought this week was not revealed, but C&C's shares have been changing hands at around €4.50 (£3.70).
At that price the investment manager would have had to fork out more than €15 million (£12.4m) to snap up the additional shares.
Last month, C&C said total Tennent's volumes in the first nine months of its financial year had dipped by 4.7% with net revenue falling by 2.9%.
But the Caledonia Best ale along with Belgian beer brand Heverlee were both said to have continued to grow volumes in Scotland.
C&C has invested heavily in the Wellpark Brewery in Glasgow since buying Tennent's from Anheuser-Busch InBev for £180m in 2009.
Last year, it unveiled plans for a joint venture with Alloa-based Williams Bros to build a new craft brewery and brewing centre of excellence in the Drygate area of Glasgow, next to Wellpark.
Shares in C&C closed up 12 cents, or 2.55%, at €4.62.