They are separate legal entities - Salu may go out of business but the holding company just lost the share values and nobody else is liable for anything.
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The defining feature of a corporation is its legal independence from the people who create it. If a corporation fails, shareholders only stand to lose their investment, and employees will lose their jobs, but neither will be liable for debts that remain owing to the corporation's creditors. This rule is called limited liability, and it is why corporations end with "Ltd." (or some variant like "Inc." and "plc").