US broadband equipment supplier Adtran tried to hide disappointing news of a downward trend in trading to the “graveyard” slot between Christmas and the New Year. It said that its likely revenue for Q4 would be closer to $125 million than its Q3 result which was $185 million and its earlier guidance for Q4 of $161.3 million, almost a $40 million shortfall. Investors will be shocked by the 25% miss, and are likely to run for the hills. Its share price fell 12% on the news, which has to constitute a let off – there may be more falls to come. Adtran said that non-GAAP earnings would be miniscule and that a full GAAP calculation would lead to a loss…