(Bloomberg) -- The nonprofit that was UL Solutions Inc.’s sole backer before the safety firm’s initial public offering in April is selling 20 million of its shares, following a startling post-IPO run up.

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UL Solutions shares closed at $54.10 each on Tuesday, up 93% from where the stock was sold in the $946 million IPO, giving the company a market value of $10.8 billion. At the closing price, the stake would be worth $1.1 billion, according to Bloomberg calculations.

After the close of regular trading Tuesday, UL Solutions shares dipped about 4.6% to $51.60 apiece on light volume.

The offering consists entirely of existing shares to be sold by UL Standards & Engagement, according to a statement. The underwriters have an option to buy an additional 3 million shares from the nonprofit.

Goldman Sachs Group Inc. and JPMorgan Chase & Co. are leading the sale, the statement showed.

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