NEW YORK ( TheStreet Ratings) -- Ratings ranked 14,577 open-end stock mutual funds offered by 461 different fund families on the basis of risk-adjusted return for our Spring 2012 Guide to Stock Mutual Funds. The top 30% of funds with grades of B+ or better are considered to be 'Buys', the middle 40% 'Holds' have grade in the C range, and the lower 30% 'Sells' have grades of D+ or worse.

The fund families placing a higher percentage of their funds in the top 30% of our year-end rankings than their peers are considered to be 'Ultra' fund families. Peer groups include fund families with 100 or more rated funds, 40 to 99 rated funds, 10 to 39 rated funds, and 1 to 9 rated funds.

T. Rowe Price Funds, a unit of T. Rowe Price Group ( TROW - Get Report) placed 54 of its 122 rated funds in the top 30% of TheStreet Ratings ranking of open-end stock mutual funds. So, T. Rowe Price wins top 'Ultra' fund family honors among families with 100 or more rated funds.

See the list of the top rated T. Rowe Price funds in our Ratings Research Center. The list includes A+ rated funds such as T Rowe Price Blue Chip Growth ( TRBCX - Get Report) and T Rowe Price Media and Telecomm ( PRMTX - Get Report).

The runner-up 'Ultra' fund family in the 100 plus group is Vanguard Funds. Vanguard finished the year with 99 of its 236 rated funds in the 'buy' range of B+ or better.

See the list of the top rated Vanguard funds in our Ratings Research Center. The list includes A+ rated funds such as Vanguard Consumer Discn Index Adm ( VCDAX - Get Report) and Vanguard Mega Cap 300 Gr Index I ( VMGAX - Get Report).

Both T. Rowe Price and Vanguard maintained their positions as the top two fund families ranked at year-end as listed in TheStreet Ratings 2012 Ultra Fund Families article.

Topping the 'Ultra' fund family list of large groups with 40 to 99 rated funds are three families that all placed more than 45% of their rated funds in the top 30% of our rankings. Munder Funds outperformed its peers with 48.8% of its 41 rated funds in the 'buy' range.

Highmark Funds is the runner-up with 45.8% of its 48 rated funds on top. Delaware Investments slipped to third place on 45.7% of its 94 rated funds in the top rank.

While none of these three families have their own top rated funds page, you can still view a find a list of their funds in our mutual fund screener. For example, click on the "FUNDS" tab. Select "Munder Funds" from the "Fund Family" drop-down menu. Then drag the lower bound "Overall Rating" slider to the left so that only funds rated in the green range from A+ down to B- are shown including A rated Munder Growth Opportunities A ( MNNAX - Get Report).

The smaller 'Ultra' fund family list of groups with 10 to 39 rated funds is led by Hotchkis & Wiley Funds with all 17 of their rated funds in the top 30% of our rankings. The Hotchkis & Wiley Value Opportunities A ( HWAAX - Get Report) and Hotchkis & Wiley Large Cap Val I ( HWLIX - Get Report) both earned 'Excellent' rating of "A" for the period ending Mar 31, 2012.

The Brown Advisory Funds group retained second place with 90.9% of their 11 rated funds in the 'buy' range including A+ rated Brown Advisory Growth Equity Adv ( BAGAX - Get Report) .

The Wasatch Funds, slipped from first place last quarter, to third with 11 of 13 fund ranked as top rated. This earns an honorable mention with A+ rated funds such as the Wasatch Core Growth Investor ( WGROX - Get Report).

Of the fund families with less than 10 rated funds, the 'Ultra' fund family winner is Baird Funds with all four of their funds ranked at 'buy' including the A+ rated Baird MidCap Inv ( BMDSX - Get Report).

No less impressive, Olstein Funds tied for first place with all four of their rated funds on top including the A+ rated Olstein All Cap Value Adv ( OFAFX - Get Report).

Two fund families tied for second place with all three of their funds ranked in the top 30%. Ariel Focus Investor ( ARFFX - Get Report) is the highest rated fund from Ariel Funds at B+. Lateef I ( LIMIX - Get Report) is the highest rated fund from Lateef Funds at A+.

Research Methodology Ratings condenses the available fund performance and risk data into a single composite opinion of each fund's risk-adjusted performance. This allows the unbiased identification of those funds that have historically done well and those that have underperformed the market.

While there is no guarantee of future performance, these Investment Ratings provide a solid framework for making informed, timely investment decisions. In order to qualify for a rating, an open-end fund must either have three years of risk and return data or be an additional share class of an existing fund with at least three years of performance statistics. Some related fund families of the same parent company have been grouped together.

Funds rated A or B are considered "Buy" rated based on a track record of higher than average risk-adjusted performance. Funds at the C level are rated as "Hold," while underperformers at the D and E levels our model ranks as "Sell."

-- Reported by Kevin Baker in Jupiter, Fla.

Kevin Baker became the senior financial analyst for TheStreet Ratings upon the August 2006 acquisition of Weiss Ratings by, covering equity and mutual fund ratings. He joined the Weiss Group in 1997 as a banking and brokerage analyst. In 1999, he created the Weiss Group's first ratings to gauge the level of risk in U.S. equities. Baker received a B.S. degree in management from Rensselaer Polytechnic Institute and an M.B.A. with a finance specialization from Nova Southeastern University.