(Bloomberg) -- Brookfield Business Partners LP had its worst trading day since October after one of its top investments, a software provider for car dealerships, fell victim to a cyberattack.

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Canadian-listed shares of the Toronto-based private equity firm closed down 5.7% on Thursday after CDK Global, a company relied on by automotive dealerships in the US to run their services, was hacked for a second time.

Brookfield Business Partners listed CDK Global as one of its “Super Six” investments in its 2023 investor day presentation, naming the top six holdings that also include Clarios, DexKo Global Inc., Westinghouse, Sagen MI Canadian Inc. and Scientific Games.

(Updates closing share price)

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