Shares in data center company and real estate investment trust (REIT) Equinix (EQIX -7.92%) were lower by nearly 10% by noon ET today. The decline comes after a slew of Wall Street analysts downgraded the stock the day after its analyst day presentation.Here's what the investment community is worried about.Analyst downgradesIn truth, the decline is probably a combination of lofty expectations going into the analyst day presentation (not least because data centers and artificial intelligence, or AI, are the ...