Shares of Delek US Holdings (Ticker: DK) are up more than 40 percent so far in 2013 and more than 170 percent over the past 12 months. And while they took a bit of a breather of late, Jack Hough at Barron's over the weekend wrote that the oil refiners active in the center of the country will continue to benefit from the difference between what they pay for the West Texas Intermediate crude and what consumers are paying for refined products, which are based more on the price of Brent oil. That dynamic is expected to be a temporary one — even though it's persisted for a good while — and one analyst says that is creating a virtuous cycle of sorts.

Belief that the refiner boom will end keeps investment low. That strains capacity and keeps the boom running. Over the past six quarters, Wall Street analysts have consistently underestimated refiner earnings. They still are.

Cantor Fitzgerald analyst Joe France has lifted his price target for shares of hospital chain Vanguard Health Systems to $18 from $17. He has reiterated his 'buy' rating on the company, whose shares (Ticker: VHS) have climbed 40 percent over the past three months and are now changing hands around $14.70.

David Gagliano at Barclays Capital didn't do Noranda Aluminum shareholders any favors Thursday when he lowered his price target for the Franklin-based company to $7 from $8 following its Q4 report. Noranda (Ticker: NOR) shares gave up more than 11 percent Thursday but are recovering a bit this morning. In early trading, they were changing hands around $5.10.

Executives from Bridgestone Metalpha, the steel cord division of the global tire giant, gathered with Montgomery County officials this week in Clarksville to break ground on a 123,000-square-foot expansion that's been in the works for a while. Bridgestone officials announced their plans to grow in Clarksville in 2011 and began prepping the site early last year. The expansion will grow the plant’s capacity by 10 percent and add 47 jobs to the 420 people already there. Construction is expected to wrap up late next year.

From left: EDC President and CEO James Chavez, EDC Chairman Steve Kemmer, County Commissioner Charles Keene, County Mayor Carolyn Bowers, Clarksville Mayor Kim McMillan, Bridgestone Corp. Steel Cord Management Director Yuuji Mochizuki, Bridgestone Metalpha President Yoshi Yamada, EDC Board Member Jim Durrett, Plant Manager Donna Bright, Bridgestone Americas U.S. and Canada Commercial Tire Sales Division President Ken Weaver, State Sen. Mark Green, IDB Board Member Billy Atkins and IDB Executive Director Mike Evans

It's time to back away from buying Delek US Holdings, says Roger Read at Wells Fargo Securities. He has trimmed his recommendation for shares of the Brentwood-based oil refiner and marketer to 'market perform' from 'outperform.' Nevertheless, he has raised his price target range to $39 to $41 from $35 to $37 and says the refining sector should continue to do well. Read's move took its tool Wednesday, though: The stock (Ticker: DK) fell almost 6 percent, trimming its year-to-date gains to "only" 45 percent.

Also taking a hit Wednesday was LifePoint Hospitals, which slipped more than 2 percent — likely because of the broader market malaise — even though UBS analyst A.J. Rice raised his target to $48 from $46. Rice reiterated his 'neutral' rating on the shares of the Brentwood-based hospital chain (Ticker: LPNT).

Ingram Content Group says it will next month begin to handle on-demand printing and fulfillment for publishers of journals. The services will be run out of La Vergne at first and the company says it expects to be able to help its clients save on overprinting and warehousing.

The Renault-Nissan Alliance has expanded its Silicon Valley presence following the unveiling of an advanced research center to initially specialize in autonomous driving and connected cars.

Today marks the official opening of the Nissan Research Center Silicon Valley (NRC-SV), which will enhance Nissan's global research capability through collaborative partnerships with companies and research institutions in this global technology hub.

The opening of NRC-SV is part of Nissan's global strategy to expand and localize its R&D function in strategic markets. The new Silicon Valley research center will take responsibility for selected roles in collaboration with Nissan Research Center in Japan.

The initial projects that Nissan researchers will pursue include:

1. Research of autonomous vehicles to realize a future with safe, stress-free mobility;
2. Research of connected vehicles that can tap into infrastructure and the Internet to maximize energy and time efficiency; and
3. Research in the area of Human Machine Interface to enhance the experience of autonomous and connected vehicles.