运营者术语表
Top-of-search impression share（头部展示份额 / TOS IS）
衡量你的广告在搜索结果首屏头部这块位置上赢下了多少可竞得的展示，分母是桌面端前 5 个、移动端前 4 个头部位置，只有 Sponsored Products 和 Sponsored Brands 才有这个指标。
最容易踩的是颗粒度：精准匹配上的 TOS IS 可以直接读，广泛、词组、自动和 product targeting 上则是你看不见的一堆搜索词的加权平均——面上 40%，可能长尾 90%、大词只有 5%。Search Term Impression Share 补不回来，它的分母是所有广告主在该词上的全部展示且不分位置。target 级到底支不支持，Amazon 自己的 Ads API v3 文档两处对不上，建议先自己拉一次确认。第二个坑在出价：位置竞价调整是叠加在 bidding strategy 之上而不是封顶——Amazon 的例子是 $1.00 动态出价加 50% 变 $1.50，dynamic bidding（up and down）最多还能推到 $3.00。Amazon 从没公布过任何达标基准，所以只当方向性诊断：要干净颗粒度就用单关键词广告活动，一次只动一个乘数，等过 12 小时延迟再看。
关键数字
费率与规则以官方英文原文为准，保留原文：
- The metric covers Sponsored Products and Sponsored Brands only, and Amazon defines top of search (first page) as up to the first 5 positions in the top row of page-one results on desktop and up to the first 4 on mobile.
- It carries a 90-day lookback, may be delayed by up to 12 hours in campaign manager, and appears in no Sponsored Display, Sponsored Television or search term report.
- Amazon's own Ads API v3 documentation is inconsistent about grain — the columns reference lists topOfSearchImpressionShare for spCampaigns, sbCampaigns and sbTargeting while the targeting report page also lists it as a base metric for spTargeting — so verify target-level availability yourself before building rules on it.
官方来源：Amazon Ads - Top-of-search impression share metric announcement · Amazon Ads Support - Adjust Sponsored Products bids · Amazon Ads API - Reporting columns (version 3), topOfSearchImpressionShare
本词条另有英文完整版。