Editing CAC 40 (section)

==Rules==

===Selection===
The CAC 40 index composition is reviewed quarterly by an independent Index Steering Committee ({{langx|fr|Conseil Scientifique}}).<ref name="profile" /> If any changes are made, they are
effected a minimum of two weeks after the review meeting.<ref name="profile" /> At each review date, the companies listed on Euronext Paris are ranked according to [[Float (finance)|free float]] [[Market capitalization|market capitalisation]] and [[stock|share]] turnover over the prior 12 months.<ref name="rules">{{cite web
 |url          = http://www.euronext.com/fic/000/050/871/508718.pdf
 |title        = Rules for the CAC 40 Index
 |publisher    = Euronext
 |date         = January 2009
 |access-date   = 2009-12-17
 |archive-url  = https://web.archive.org/web/20110616051936/http://www.euronext.com/fic/000/050/871/508718.pdf#
 |archive-date = 16 June 2011
 |url-status     = dead
}}</ref> From the top 100 companies in this ranking, forty are chosen to enter the CAC 40 such that it is "a relevant benchmark for [[Investment management|portfolio management]]" and "a suitable underlying asset for [[Derivative (finance)|derivatives]] products".<ref name="rules" /> If a company has more than one class of shares traded on the exchange, only the most actively traded of these will be accepted into the index (generally this will be the ordinary share).<ref name="rules" />

===Weighting===
The CAC 40 is a [[capitalization-weighted index]]. The number of shares issued (used to calculate the market cap and hence the index weight) of a company is reviewed quarterly, on the third Friday of March, June, September and December.<ref name="profile" /> Since December 2003, the index weightings of companies in the index have been capped at 15% at each quarterly index review,<ref name="rules" /> but these range freely with [[share price]] subsequently. A capping factor is used to limit the weights to 15% (if necessary), and is reviewed annually by the Index Steering Committee on the third Friday of September.<ref name="rules" />

===Calculation===
The index value I of the CAC 40 index is calculated using the following formula:<ref name="rules" />
<math> I_t = 1000\times\frac{\sum_{i=1}^N Q_{i,t}\,F_{i,t}\,f_{i,t}\,C_{i,t}\,}{K_t\,\sum_{i=1}^N Q_{i,0}\,C_{i,0}\,} </math>
with ''t'' the day of calculation; ''N'' the number of constituent shares in the index (usually 40); ''Q<sub>i,t</sub>'' the number of shares of company ''i'' on day ''t''; ''F<sub>i,t</sub>'' the free float factor of share ''i''; ''f<sub>i,t</sub>'' the capping factor of share ''i'' (exactly 1 for all companies not subject to the 15% cap); ''C<sub>i,t</sub>'' the price of share ''i'' on day ''t''; ''Q<sub>i,0</sub>'' the number of shares of company ''i'' on the index base date; ''C<sub>i,0</sub>'' the price of equity ''i'' on the index base date; and ''K<sub>t</sub>'' the "adjustment coefficient for base capitalization" on day ''t'' (reflecting the switch from the French franc to the [[Euro]] in 1999).

=== Contract specifications ===
The CAC 40 index is traded as a future on the Euronext Equities & Index Derivatives (EUREID) exchange under the ticker symbol PIL.
{| class="wikitable"
|+Contract Specification<ref>{{Cite web |title=Historical CAC 40 Intraday Data (PIL) |url=https://portaracqg.com/historical-futures-data/cac-40-intraday-data/ |access-date=2022-10-28 |website=PortaraCQG |language=en-US}}</ref>
!CAC 40 (PIL)
!
|-
|Exchange: 
|EUREID 
|-
|Sector: 
|Index 
|-
|Tick Size: 
|0.5 
|-
|Tick Value: 
|5 EUR 
|-
|Big Point Value (BPV): 
|10 
|-
|Denomination: 
|EUR 
|-
|Decimal Place: 
|1 
|}