Reducing Betterment's CPA by 10% With a Custom Bidding Script

Converting Valuable Audiences at a Low CPA

Financial services firm Betterment set out to strengthen its paid media campaigns by boosting conversions while focusing on customers with genuine long-term value.

Although Betterment saw solid results with Google Ads’ standard bidding strategies, the built-in features couldn’t fully capture the nuanced, proprietary signals that identified their most valuable customers.

Adswerve, Betterment's longtime managed media services partner, proposed a custom script for advanced, real-time bidding. This approach could respond to small market shifts, drive conversions aligned with their specific business goals and lower their CPA.

We collaborated to develop a solution to meet their needs.

Engineering Smarter Bidding

We kicked off the project by conducting a workshop to discuss and analyze Betterment’s historical performance data and customer value metrics. The collaborative work allowed us to identify key signals that correlate with long-term customer success. 

Using this information, we developed a custom bidding script for Google Display & Video 360 (DV360). It automates complex bidding decisions for the Betterment team while also providing a new level of control over their strategy.

When developing the script, we incorporated a dynamic, weighted, three-tier scoring system to prioritize valuable conversions, such as retail brochure site visits, signup completions and initial deposit conversions. 

We then ensured the script dynamically adjusts bids using a multiplier based on factors like viewability (to prioritize impressions more likely to be seen), dayparting (to optimize for times when the audience is most engaged) and creative dimensions (to favor ad sizes that historically drove stronger engagement). 

Finally, we spent three months (split into two phases: learning and optimizing) comparing the performance of our custom script against both fixed and Google-automated bidding strategies to measure the impact. 

Maximizing Spend Efficiency

Implementing the new custom bidding script delivered significant, measurable reach and cost improvements for Betterment's paid media campaigns, especially after the initial six-week learning period.

Despite some initial budget-related fluctuations where non-custom bidding showed higher conversion volume, the custom bidding script consistently demonstrated its ability to spend budget in full while reaching a wider audience, with increased reach, a slightly higher CTR and impression volume and a 10% lower CPA.

The custom bidding script generated 40% more impressions and 1.7K additional clicks for retargeting campaigns, achieving an eCPM approximately 50% lower compared to auto-bidding for the same conversion volume. 

By the end of our three-month testing period, impression and click reach had become nearly equal for both methods, indicating the platform's successful adoption of the script.

When examining daily spend and conversion rates, we found that custom bidding required nearly 30% less daily spend than automated bidding to achieve the same CPA below $300. This efficiency became particularly evident after the initial learning period, when conversion results began to shift significantly toward the custom bidding script, with a 66% increase in conversion total.

Now, the Betterment team can be confident they’re maximizing their budget for the highest potential return.

Up next? Applying our learnings to additional custom script development, focusing on mid-funnel conversions like page views and button clicks, to drive even greater ROI for Betterment.