A common question advertisers raise is: what’s the difference between cross-channel bidding within one, unified campaign vs. portfolio bidding with a shared budget across multiple campaigns that cover different channels?
Cross-channel bidding from one unified campaign like Performance Max vs. adding single-channel campaigns to a portfolio bid strategy with a shared budget
A portfolio bid strategy lets you group together multiple campaigns and apply the same bid strategy and target to all of them. A shared budget lets multiple campaigns draw from one common budget. It provides helpful “overdraft protection” and allows a campaign to keep running using the shared budget rather than being capped by its own individual budget.
But this approach has its limitations. Here are some of the drawbacks:
- Limited channel coverage: Portfolio bid strategies are not available for all channels. They can only be used with Search, Display, and Shopping campaigns. In comparison, a complete cross-channel bidding strategy in one unified campaign such as Performance Max allows you to bid across all ad channels—including YouTube, Discovery, Gmail and Maps—at the same time.
- No optimisation and learning between channels: You can’t optimise bids between channels using portfolio bid strategies. For example, portfolio bid strategies will optimise bids between multiple Search campaigns towards the target CPA or ROAS you set. However, they won’t optimise towards a joint CPA or ROAS across different channels and inventory. For example, a Search campaign and Shopping campaign in a portfolio strategy will not optimise towards the CPA or ROAS target together.
Overall, portfolio bid strategies with shared budgets are helpful as a management tool to distribute budget fluidly among campaigns and avoid constraining performance if one campaign becomes budget capped. They’re useful for optimisation within a single channel and we encourage you to use them for a collection of Search campaigns. But the conversion opportunities with the highest marginal ROI for your business may also be on channels not available with portfolio bid strategies. To truly maximise your results and grow performance, it’s important to focus on your goals rather than the individual channels that your ads appear on.
