brmarket

Go package to fetch index composition from B3, the Brazilian stock exchange. Given an index symbol (e.g. IBOV), it returns the constituent securities and their theoretical weights.

Each call makes a live HTTP request to B3's public IndexComposition endpoint, so it needs network access and can fail with network, status, or decoding errors.

Install

go get github.com/cesarvspr/brmarket/v2

Usage

package main

import (
	"fmt"
	"log"

	"github.com/cesarvspr/brmarket/v2"
)

func main() {
	info, err := brmarket.GetSharesForIndex(brmarket.IBOV.String())
	if err != nil {
		log.Fatal(err)
	}

	fmt.Printf("%s (%s): %d constituents\n",
		info.Index.Symbol, info.Index.Description, len(info.UnderlyingList))

	for _, c := range info.UnderlyingList {
		fmt.Printf("  %-6s %.3f%%\n", c.Symb, c.IndxCmpnPctg)
	}
}

Context, deadlines, cancellation

Use GetSharesForIndexContext to control the request lifetime:

ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()

info, err := brmarket.GetSharesForIndexContext(ctx, brmarket.IBOV.String())

GetSharesForIndex is a thin wrapper that calls this with context.Background() and a default 15s client timeout.

Errors

Errors are wrapped and can be matched with errors.Is:

_, err := brmarket.GetSharesForIndex("NOPE")
if errors.Is(err, brmarket.ErrIndexNotFound) {
	// unsupported symbol
}

Sentinel	Meaning
ErrIndexNotFound	the symbol is not a supported B3 index
ErrUnexpectedStatus	B3 returned a non-200 HTTP status
ErrUnexpectedResponse	B3 returned 200 but the body was not a valid index composition

Working with index symbols

idx, err := brmarket.ParseIndexType("IBOV") // brmarket.IBOV, nil
sym := brmarket.IBOV.String()               // "IBOV"

Supported indexes

IBOV  IBXX  IBXL  IBRA  IGCX  ITAG  IGNM  IGCT
IDIV  MLCX  SMLL  IVBX  ICO2  ISEE  ICON  IEEX
IFNC  IMOB  INDX  IMAT  UTIL  IFIX  IFIL  BDRX
GPTW  IDVR  IBLV  IBSD  IBHB

License

MIT