It's time for investors to join the tech bubble, according to Citi. The Wall Street firm said tech stocks officially entered a bubble in May after their extraordinary run-up. "The tech sector has entered a bubble, but we believe there is still time to join the hype, not fade it," strategist Hannah Sheetz wrote to clients Tuesday, following a review of 28 sector bubbles over the last four decades. .IXIC YTD mountain Tech in a bubble, Citi says The analyst said tech bubbles usually return 6.4% in addition to the market for the first six months after the signal flashes. "Historically, a tech bubble will stay inflated for a median of 23 months before hitting our bubble exit condition.

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Persons: Hannah Sheetz, Sheetz, — CNBC's Michael Bloom Organizations: Citi, Nvidia, Tech