Purchase a dataset that lists all the changes to the S&P 100 index composition since 1/1/1991, including a summary sheet that allows you to quickly check the past components for any date. Check a sample file from here.
Changes to S&P 100 composition during 2017, 2016 & 2015
During 2017, Charter Communications Inc (CHTR) replaced DuPont (DD). DuPont completed its merger with Dow Chemicals in August 31, 2017.
During 2016, three components were replaced. Danaher Corp (DHR), Duke Energy (DUK) and Nextera Energy Inc (NEE) were added to the index and Norfolk Southern Corp. (NSC), Devon Energy Corp. (DVN) and Anadarko Petroleum Corp. (APC) were removed in March 2016.
During 2015, six components were replaced by other companies. In March 2015, Celgene Corp, Kinder Morgan Inc and Allergan plc were added to the index. Priceline Group was added in June and PayPal Holdings in July. In September, additional share classes of 21st Century Fox (FOX) and Comcast (CMCSK) were added. BlackRock replaced Hewlett-Packard on October. The last change to the index happened in December when the additional share line of Comcast was removed when CMCSK and CMCSA lines were combined.
How often do the components change?
Compared to NASDAQ-100 or S&P 500 indexes, the components of S&P 100 change quite rarely. S&P Dow Jones prefers keeping the components as steady as possible and even a large drop in a company’s market capitalization does not necessarily lead to deletion from the index. During the past 11 years, the average number of changes to the index is six replacements per year. The most common reason for shuffling the components is mergers & acquisitions. Read more details from the official page of S&P 100.
S&P 100 index
Standard & Poor’s 100 Index includes 100 major companies that are listed on the NYSE or NASDAQ exchanges. Currently, the index consists of 102 constituents: Alphabet (GOOGL & GOOG) and 21st Century Fox (FOXA & FOX) have both two different share classes part of the index.