Excel & Google Sheets Financial Underwriting Guide

1. Overview & Why It Matters

Financial analysts, acquisitions associates, and portfolio managers spend over 80% of their workday inside Microsoft Excel and Google Sheets. Traditional financial portals force analysts to manually look up SEC 10-K filings, copy-paste dividend payout ratios, and recalculate cap rates by hand.

The REITwave Spreadsheet Engine converts REITwave from a standalone website into a dynamic quantitative engine embedded inside your underwriting models. When you open your acquisition DCF or dividend income planner, formulas update instantly with fresh institutional data across 207 US REITs.

2. Google Sheets Quickstart (60 Seconds)

Google Sheets executes custom functions via Google Apps Script and REITwave's ultra-fast REST endpoints. Setup takes under a minute and requires zero browser extensions.

/**
 * REITwave Google Sheets Custom Function Connector
 * Official Formula Engine: =REITWAVE(ticker, metric, [apiKey])
 */
function REITWAVE(ticker, metric, apiKey) {
  if (!ticker || !metric) return "#N/A: Missing ticker or metric";
  
  var cleanTicker = ticker.toString().trim().toUpperCase();
  var cleanMetric = metric.toString().trim().toUpperCase();
  
  // Script cache prevents spamming API recalculations
  var cache = CacheService.getScriptCache();
  var cacheKey = "rw_" + cleanTicker + "_" + cleanMetric;
  var cachedVal = cache.get(cacheKey);
  if (cachedVal !== null) {
    var num = Number(cachedVal);
    return isNaN(num) ? cachedVal : num;
  }
  
  var url = "https://reitwave.com/api/sheets/quote?ticker=" + encodeURIComponent(cleanTicker) + 
            "&metric=" + encodeURIComponent(cleanMetric) +
            (apiKey ? "&api_key=" + encodeURIComponent(apiKey) : "");
            
  try {
    var response = UrlFetchApp.fetch(url, { muteHttpExceptions: true });
    if (response.getResponseCode() !== 200) {
      return "#ERROR: " + response.getContentText();
    }
    var data = JSON.parse(response.getContentText());
    var value = data.value;
    
    // Cache result for 10 minutes (600s)
    cache.put(cacheKey, value.toString(), 600);
    
    var num = Number(value);
    return isNaN(num) ? value : num;
  } catch (err) {
    return "#ERR: Connection failed";
  }
}

/** Convenience formula for live stock price */
function REITPRICE(ticker) {
  return REITWAVE(ticker, "PRICE");
}

/** Convenience formula for live AFFO yield */
function REITAFFOYIELD(ticker) {
  return REITWAVE(ticker, "AFFO_YIELD");
}

3. Microsoft Excel Setup (Office.js)

Modern Excel (Microsoft 365, Excel Online, Mac, and Windows Desktop) uses Office.js Custom Functions defined by an XML manifest.

4. Supported Financial Metrics Reference

The =REITWAVE(ticker, metric) formula resolves over 15 key fundamental metrics. Metric names are case-insensitive.

5. Commercial Tiers & API Keys

To ensure sustainable low latency across institutional spreadsheets, REITwave formulas are tiered based on membership level:

6. Caching & Latency Architecture

To ensure your spreadsheet does not freeze or trigger rate limits when running 100+ formulas simultaneously, the REITwave Add-in incorporates a multi-layer caching architecture:

• Apps Script CacheService (10-minute TTL): Recalculating a spreadsheet does not re-fetch existing cells; it retrieves values directly from memory in < 5ms.
• In-Memory Universe Engine: REITwave's backend caches valuation models and live prices in memory, resolving requests in < 15ms.
• Graceful Degradation: If a non-existent ticker or metric is entered, formula returns descriptive errors (#N/A: Ticker Not Found) rather than silent zeros.

7. Frequently Asked Questions (FAQ)