Mistaken Ghost Order Caused Worst India Trading Blunder in Years

One of India’s biggest trading blunders in recent years occurred because of a mistaken case of a ghost order, according to people familiar with the matter.

On Thursday morning in Mumbai, traders at Spark Institutional Equities Pvt. uploaded data to execute an order to sell as much as 24% of Clean Science & Technology Ltd. on behalf of the founding Boob family for about $300 million, a block sale that would reduce the clan’s ownership just enough to keep a majority stake.

But that order didn’t appear to go through, prompting the traders at Spark, a unit of Avendus Capital ...