Warren, N.J.-based insurer The Chubb Corp. is calling upon investors to reject an unsolicited "mini-tender" offer from TRC Capital Corp., which has a history of such questionable practices.

Chubb told investors that the offer to purchase up to two million shares, or about 0.6 percent of the company's common stock, would be at a discount of 4.35 percent of the closing price of $49.14 as of May 26. TRC is offering $47 per share.

The sale would also be subject to numerous conditions, "including the availability of financing on terms satisfactory to TRC in its reasonable discretion," Chubb added.

"Chubb does not endorse TRC's offer and recommends that shareholders do not tender their shares in response to the offer," the carrier said.

Chubb advised investors to review a letter from the Securities and Exchange Commission (www.sec.gov/investor/pubs/minitend.htm) about mini-tender offers.

In the letter, the SEC notes that mini-tender offers (less than 5 percent of the company's stock) are designed to purchase a large share of stock without the need for filings designed to protect investors. The offer is meant to catch investors off-guard so they will sell their shares below the current value, the SEC said.

This is not the first time TRC has made such offers, and the companies targeted have told investors to reject those offers because the stock is undervalued. Among a number of companies targeted by TRC over the past few years were PepsiCo, the grocery store chain Kroger, and mining company Freeport-McMoRan.

Chubb also noted that shareholders who have tendered their shares to TRC can withdraw their shares before June 25.