If you have paper stock certificates. What to do: Stock Certificates

Keep address current on every financial account. Run easy unclaimed property search every year. Employer does not update your address. Neither cashing dividend checks, receiving direct deposits, online access, nor receiving statements prevents inactive accounts from being turned over to the state – only a personally-initiated transaction, postal response, or call. Difficult to retrieve money; stock is sold. Unclaimed Property

To be sure, also check for unclaimed stock or dividends in the original state of incorporation: Massachusetts State Treasurer

DEC sale to Compaq. Due to declining growth and profits -- including losses starting in 1990 and a $2.8 billion loss in 1992 -- DEC stock was down to $45 -- from $199 four years earlier.
Management and board negotiated the sale for a 26% premium. Announced Jan 26, 1998; completed on Jun 12, 1998. For each share of DEC owned on June 11, 1998, DEC shareholders received $30.00 in cash and  0.945 share of Compaq stock. DEC stock was retired.

HP merger with Compaq. Before the deal was announced, Compaq stock was down to $12 -- from $33 in 1999. Compaq management and board negotiated a merger at 18% over market price. (90% of Compaq shares were voted in favor; 51% of HP shares were voted in favor.)

Deal closed on May 3, 2002. HWP stock symbol was changed to HPQ. Compaq shareholders received 0.6325 share of HPQ in exchange for each CPQ share. CPQ stock was retired. (Compaq had bought Tandem on Sep 2, 1997 and bought DEC on Jun 12, 1998.)

HP Inc is the overall legal successor to Hewlett-Packard and to companies acquired by Hewlett-Packard before Nov 1, 2015 – Compaq, EDS, etc. – regardless of whether a business unit ended up in HP Inc or HPE. Unofficial directory of HP/HPE acquisitions