HP Inc. rejected a $33 billion takeover offer from Xerox Holdings Corp. as too low, but the PC and printer maker made clear it is interested in discussing a deal to combine with its smaller rival.

Xerox’s unsolicited offer of $22 a share significantly undervalues the company, HP’s board said in a public letter to Xerox Chief Executive John Visentin on Sunday. It also voiced concern about the debt a transaction would put on the combined company and said it needs more information about Xerox’s business, known as due diligence.

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