Between the May 15 and May 29 settlement dates, biotech stock MannKind continued its climb up the ranks of the most heavily shorted stocks traded on the Nasdaq. It threatens to unseat Sirius XM from the top spot, with less than 9 million shares difference between them at the end of the period.

Note that the five most shorted Nasdaq stocks all had more than 110,000 shares short at the end of the month.

The number of Sirius XM Holdings Inc. (NASDAQ: SIRI) shares short tumbled by almost 16 million to about 139.91 million late in the month. That was 6.1% of the total float, and it ended a three-period streak of rising short interest. At the current average daily volume, it would still take less than eight days to cover all short positions. Sirius was one of our back from the dead stocks during the period. Short sellers watched the share price pull back about 3% during the two weeks between settlement dates, but it is now up about 8% year to date. Shares closed Tuesday at $3.78, in a 52-week trading range of $3.14 to $4.04.

MannKind Corp.’s (NASDAQ: MNKD) short interest, at almost 131.16 million shares as of May 29, was up 16.1% from the previous period. Note that it was more than half, 51.2%, of the total float, as well as the highest short interest in at least a year. The days to cover dropped from more than 14 to less than 13. In late May, it looked like Mannkind shares had found bottom. Shares ended Tuesday at $6.70, in a 52-week range of $3.46 to $11.48. The stock saw a share price increase of more than 41% in the two-week short-interest period, and another 43% or so since.

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