Getting a boost for the week were Fremont General Corp, Prospect Medical Holdings Inc. and RadNet Inc. Slipping were Peerless Systems Corp. and Arrowhead Research Corp.

Fremont got a boost thanks to the Santa Monica lender finding a buyer for its commercial mortgage business. The sale prompted a credit-rating boost from Standard & Poor’s, sending shares up 63 percent for the week to $11.73.

Prospect saw shares gain 23 percent after the Culver City health care management company announced it had acquired Ontario-based ProMed Health Care, making Prospect one of the largest manager of physician groups in the state. Shares closed the week at $4.95.

Shares in RadNet shot up 16 percent for the week after the Los Angeles-based diagnostic imaging services provider said it had acquired Borg Imaging Group of Rochester, N.Y. Shares in RadNet closed Friday at $6.58.

Losing market cap was Peerless, which saw shares fall 12 percent after the El Segundo-based imaging technology provider posted a first-quarter loss of $829,000. Shares closed the week out at $2.53 per share.

Arrowhead Research took a hit after it was rumored that a handful of hedge funds were set to dump stock of the Pasadena company, which commercializes nano-based technologies. Shares sank 9 percent to close Friday at $6.35.