How we calculate the IGAB indices

A family of five indices

Each index is calculated independently over its own basket. The IGAB covers the whole market; the others isolate one asset class.

• IGAB

  General Index

  Every asset with an active BODIVA listing.

• IGAB-EQ

  Equity Index

  Equities only.

• IGAB-BD

  Bond Index

  Bonds only.

• IGAB-FD

  Fund Index

  Investment funds only.

• IGAB-FI

  Fixed Income Index

  Bonds plus fixed-income and money-market funds.

Who makes the basket

Every instrument with an active BODIVA listing and an active issuer is included. There is no selection committee and no manual picking: if it is listed and active, it counts.

When an asset is admitted to or removed from the exchange, the composition is rebuilt and the divisor is adjusted so the index does not jump.

The formula

We add up the market value of every asset in the basket and divide it by a fixed number, the divisor. The divisor is set at inception so the index opens at 1,000 points, the baseline.

Above 1,000, the market is worth more than it was on the base date. Below, it is worth less.

How each asset is valued

Each asset enters at its market value, and its weight is that value divided by the basket total. Whatever is worth more, weighs more.

• Equities and funds: price × issued quantity.
• Bonds: price as a percentage × face value × issued quantity. Bonds trade as a percentage of face value, and the calculation respects that.

The divisor and continuity

The divisor exists for one thing: keeping the series continuous. When the basket composition changes, we recalculate the divisor so the index value stays exactly where it was. The next move reflects the market, not the composition change.

Safeguards

An index is only reliable if it can handle imperfect data. Rules we apply:

• An index is only published with at least two valid constituents.
• Assets without a valid price or quantity stay out of the calculation until data is available.
• Bonds without a known face value do not contribute to the index.
• Every value is recorded with the day open, high and low, and the daily history is preserved.

When it is recalculated

The index recalculates automatically whenever new BODIVA data arrives, throughout the whole session. Outside trading hours, the last session value stands.

Limits and evolution

We would rather say what the index does not do yet than pretend it does everything.

• Weights use the full issued quantity, with no free-float adjustment.
• There is no cap on the weight of a single asset: the basket reflects the real concentration of the Angolan market, where public debt dominates.
• We apply no liquidity screens at admission.

As the market matures, the methodology evolves. Any change will be announced and the history preserved.