The shares had hovered barely above the $14 issue price ever since last Friday's initial public offering, before dropping five percent to $13.29 in Thursday morning trade on the New York Stock Exchange.
They bounced back slightly to $13.50 in after midday.
The heavily indebted club went public in the United States last week following aborted efforts to do so in Hong Kong and Singapore, where the American owners, the Glazer family, had hoped that its large Asian fan base would happily pay a premium for the shares.
In the end the IPO price had to be cut for the 16.7 million shares from the expected $16-20 range due to weak demand amid doubts that the management would be able to substantially boost club profits.
The exercise pulled in $234 million, with half going to the Glazers and only $101.7 million to reducing the pre-IPO debt burden of 423 million pounds ($660 million).
It nevertheless left the Cayman-registered Manchester United Ltd the world's most highly valued sports team, with a market worth of $2.3 billion based on the IPO price.