Is the DJIA Index Biased

Since 1997, the Dow Jones Industrial Average (DJIA) Index has replaced companies in the index on six occasions. Overall, 16 companies have been dropped from the index. The first four replacements involved dropping and then replacing companies that still existed. These four discretionary substitutions may potentially have biased the Dow. The most recent changes were made because of terminal events; not replacing these companies would have left the Dow with fewer than 30 companies.