In over 20 years of helping brands measure and improve their advertising impact, we’ve found a striking pattern: nearly every brand we’ve worked with—bar one—was underinvesting in advertising. In every case, increasing spend would have driven incremental sales at a positive ROI (including time-discounted future cash flows).

And we’re not alone. Other seasoned practitioners report similar findings.

The only analytical approach that reliably reveals this underfunding—and prescribes how to fix it—is a properly built Marketing Mix Model (MMM). Not just any MMM, but one grounded in these five principles:

• C-suite alignment – built to support executive-level goals
• Accuracy – explains over 90% of historical sales variation and maintains predictive strength
• Actionability – directly informs media buying across all channels
• Holistic scope – incorporates paid, owned, and earned media, plus baseline drivers
• Validated – tested and proven in forward-looking campaigns

At a time when brands face margin pressure and agencies are stretched thin, underfunding remains a silent killer of growth. It’s a shared problem for CMOs, CFOs, and CEOs—and a symptom of flawed budget-setting without robust analytics.

Want to unlock low-risk, high-return growth? Start by asking: Are we spending too little on advertising? Finding out pays big dividends, and if you need to upgrade your MMM to find out, that may be the best investment you can make.