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cdtweb/estimate.php

Last active Jan 4, 2021
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Simple Rolling DRIP Estimator
<?php
/*
This script will take into account your current positions and calculate your dividend reinvestment over time.
@todo Pull positions from somewhere, a local json file maybe?
@todo Pull live-ish position data so stockPrice isn't stale.
@todo Use of CLI arguments
@todo There is a bug with addMonthly that really inflates the number of shares
@todo Fractional shares on addMonthly?
@todo Turn into a class... slipper slope
*/
$positions = [
'SRET' => ['stockPrice' => 8.73, 'dividendTerm' => 'monthly', 'dividendPercent' => 8.88, 'shares' => 158.903, 'addMonthly' => 0],
'SPY' => ['stockPrice' => 369.06, 'dividendTerm' => 'quarterly', 'dividendPercent' => 1.52, 'shares' => 4.032, 'addMonthly' => 0],
];
// Calculate intial values
foreach($positions as &$pos){
$pos['value'] = number_format($pos['stockPrice'] * $pos['shares'], 2, '.', '');
}
unset($pos);
function monthlyDividends(&$positions) {
foreach ($positions as &$position) {
if ($position['dividendTerm'] == 'monthly') {
$dividendPercent = $position['dividendPercent'] / 100 / 12;
$dividendPaymentTotal = $position['shares'] * ($position['stockPrice'] * $dividendPercent);
$position['shares'] += number_format($dividendPaymentTotal / $position['stockPrice'], 3, '.', '');
$position['value'] = number_format($position['stockPrice'] * $position['shares'], 2, '.', '');
}
}
unset($position);
}
function quarterlyDividends(&$positions) {
foreach ($positions as $symbol => &$position) {
if ($position['dividendTerm'] == 'quarterly') {
$dividendPercent = $position['dividendPercent'] / 100 / 4;
$dividendPaymentTotal = $position['shares'] * ($position['stockPrice'] * $dividendPercent);
$newShares = number_format($dividendPaymentTotal / $position['stockPrice'], 3, '.', '');
$position['shares'] += $newShares;
$position['value'] = number_format($position['stockPrice'] * $position['shares'], 2, '.', '');
}
}
unset($position);
}
function addMonthlyShares(&$positions) {
foreach ($positions as $symbol => &$position) {
if (isset($position['addMonthly']) && $position['addMonthly'] > 0) {
$position['shares'] += $position['addMonthly'];
$position['value'] = number_format($position['stockPrice'] * $position['shares'], 2, '.', '');
}
}
unset($position);
}
echo "Starting positions (Symbol -> Shares -> Value):" . PHP_EOL;
foreach ($positions as $symbol => $position) {
echo "\t{$symbol} \t\t {$position['shares']} \t\t {$position['value']}" . PHP_EOL;
}
echo "Portfolio Value: " . array_sum(array_column($positions, 'value')) . PHP_EOL;
echo PHP_EOL;
$year = 1;
$years = 10;
$months = 12;
while($year <= $years){
for($i = 1; $i <= $months; $i++){
monthlyDividends($positions);
if ($i % 3 == 0) {
quarterlyDividends($positions);
}
addMonthlyShares($positions);
}
echo "Positions after year #$year (Symbol -> Shares -> Value):" . PHP_EOL;
foreach ($positions as $symbol => $position) {
echo "\t{$symbol} \t\t {$position['shares']} \t\t {$position['value']}" . PHP_EOL;
}
echo "Portfolio Value: " . array_sum(array_column($positions, 'value')) . PHP_EOL;
echo PHP_EOL;
$year++;
}
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@cdtweb cdtweb commented Jan 4, 2021

Run this like php estimate.php and the end result outputs

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