Campaign performance is influenced by many factors, let's look at some situations that may result in too much spend on campaigns.
A large boost in spend is most common in situations where we’re bidding on a high number of poor performing keywords. If you’re bidding on a lot of broad keywords or if you sourced non data backed keywords from a third party, you run the risk of having your ad show up in non-relevant searches. In these situations, you may receive clicks, but no conversions.
If you're receiving a lot of clicks, but no sales, this could be a sign that your listing needs to be optimized. Paying to drive traffic to a poorly designed page can result in wasted ad spend and poor conversion rates. Learn more about Listing Optimization.
Incorrect campaign structure can lead to overspending. The bidder uses product price to measure the payoff, if products with significant price differences are grouped together, this will lead to overspending. Learn more about Campaign Structure.
Using the wrong settings in Amazon, such as the ‘adjust bids by placement’ (booster) feature or ‘dynamic bids - up and down’ setting, will cause you to overspend. These settings interfere with our bidder, if you were to use a 50% booster in Amazon, this would automatically increase our suggested bid by 50%. For best results, use 'dynamic bids - down only' and do not set a booster. Learn more about Dynamic Bidding Strategies in Amazon.
MACS Set too High:
This also could be a result of setting a MACS too high for the category and/or having a bid floor in place for too long or incorrectly set. This could result in a spike in spend, but it will usually level out in 1-2 weeks.