(Reuters) -Alphabet, faced with unprecedented threats from AI rivals, will be keen to assure investors this week that the company’s own spending on the technology is helping it dig a deeper moat around its search and advertising businesses. Rivals of the Google parent, including AI startups such as OpenAI and Perplexity, have attracted tens of millions of users to their platforms. To maintain its grip, Alphabet has rolled out tools such as AI Overviews, which show AI-generated summaries on top of traditional links that have drawn 1.5 billion users per month, and made more Gemini models available to enterprise users.