A century-old, little-followed Minnesota stock lost nearly half of its value Monday amid a continuing controversy over the worth of Great Northern Iron Ore Properties, which will dissolve in 2015.

The price of Great Northern (ticker: GNI) fell 47 percent to $35.70 on very heavy volume after short-sellers attacked the stock, saying it was way overvalued. In response to an inquiry from the New York Stock Exchange, CEO Joseph S. Micallef, an 80-year-old lawyer and president of GNI's board of trustees, said Monday there was no internal reason for the sell-off.

Great Northern Iron Ore is the successor to the land company established by the son of James J. Hill to profit from Iron Range ore hauled by Hill's Great Northern Railway.

Micallef knew Louis W. Hill Jr., the grandson of Great Northern rail pioneer James J. Hill and the last surviving beneficiary in the trust agreement. Hill Jr. died in 1995, triggering the 20-year remaining life of the underlying trust agreement. That agreement calls for distribution of the remaining money from GNI trustees to shareholders in 2015. It also calls for the transfer at that time of GNI's mineral properties and active leases to a subsidiary of ConocoPhillips Co. After shareholders get their final distribution in 2015, the shares will become worthless.

It's long been believed that some unwitting investors looking for yield buy GNI without studying the underlying documentation.

"At the moment GNI is a bit like Wile E. Coyote after he has run off the end of the cliff," a detractor blogged on Sunday at the Seeking Alpha site. "GNI is held up by thin air…"

In 2011-12, Citron Research and other detractors helped cut the price of Great Northern from about $120 to under $70 per share by attacking the high-dividend yield paid by GNI as short-lived.

The trustees distributed $10 per share to shareholders in 2013, according to GNI. That is a hefty 15 percent dividend on Friday's closing share price of $67.07. However, the doubters say the company will have much less to distribute to shareholders in 2015.