(Bloomberg) -- Soroban Capital Partners has amassed a large stake in industrials firm Johnson Controls International Plc, compounding pressure brought by activist investor Elliott Investment Management, according to people with knowledge of the matter.

New York-based hedge fund Soroban has invested more than $500 million in Johnson Controls, making it one of the company’s top 20 investors, the people said, asking not to be identified discussing private information. 

A representative for Soroban declined to comment. A spokesperson for Johnson Controls didn’t immediately respond to a request for comment.

Pressure on Johnson Controls is mounting, with prominent activist investor Elliott building a $1 billion-plus position in the company, Bloomberg News reported Sunday. 

Read more: Elliott Said to Build $1 Billion-Plus Johnson Controls Stake

While Johnson Controls’ shares had gained 9% in the past year before Monday, it has lagged behind industrial peers such as Carrier Global Corp. and Lennox International Inc., which climbed more than 50% during the same period. 

Johnson Controls rose as much as 5.8% on Monday. The shares closed up 2.3% to $70.62 in New York trading, giving the company a market value of about $47.6 billion. 

Soroban Capital, led by Eric Mandelblatt, has $10 billion under management and invests in industrials as well as the technology consumer and payments sectors, according to a regulatory filing. The firm launched a campaign against Union Pacific Corp. last year that resulted in the departure of its top executive. 

(Updates with closing share price in sixth paragraph)

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