RA Capital Management wrote to NSTR, urging the company to make a distribution or dividend to stockholders "as soon as possible." RA Capital continues "to be shocked and frustrated by the complete lack of response" to a letter it sent in July. Although RA Capital acknowledges some steps Northstar has taken to reduce expenses, it reiterates "that now is not the time for half-measures." RA Capital intends to pursue its interests "aggressively, both for our benefit and hopefully for the benefit of all stockholders, including preserving our right to take legal action against you and the company." RA Capital currently holds 2,539,139 shares (9.71% of the total outstanding).

Former AIG Chairman and CEO Maurice "Hank" Greenberg sent a letter to current CEO Edward Liddy seeking information on special-purpose vehicles. The Greenberg group holds 271,089,903 shares (10.1%).

A group including Wynnefield Partners Small Cap Value said it's backing five directors -- one to fill a current vacancy on the board and four for seats up for re-election at White Electronic's next annual meeting. Wynnefield and Caiman Partners intend to conduct a proxy solicitation to elect William H. Alderman, Jon C. Biro, Keith Butler, Brian Kahn and Melvin L. Keating to the board. The Wynnefield Partners group holds 2,230,701 shares (9.9%).

A group of funds managed by Mario Gabelli's Gamco Investors (GBL) reported raising its stake to 1,222,840 shares (7.69%) after buying 464,900 from Oct. 20 to Dec. 10 at 59 cents to $1.87 a share.

Berkshire Hathaway (BKRA) unit National Indemnity reported that it acquired a total of around 5.5 million shares of Burlington Northern Santa Fe through the exercise of put options from Dec. 8 through Dec. 11. The options' exercise price ranged from $75 to $80 a share. Previously, National Indemnity had been filing through Schedule 13G for passive investors, but was required to change its filing status to the more detailed Schedule 13D after passing the 20% ownership threshold. National Indemnity currently holds 70,089,029 shares (20.47%).

A group of funds managed by Gamco Investors raised its stake to 610,121 Class B shares (5.71%), after buying 61,400 from Oct. 16 to Dec. 1 at $7.17 to $9.69 a share.

Fairholme Capital Management raised its holdings to 31.8 million shares (24.2%), from 22.8 million (19.65%) reported in November. Fairholme in November said it was in discussions with the consumer automobile-finance company about exchange of certain debt securities held by Fairholme for additional shares.

Oaktree Capital Group Holdings cut its stake to 2.16 million shares (6.48%) from the 2.68 million (8.04%) reported on Dec. 9.