NEW YORK ( TheStreet Ratings) -- TheStreet.com 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) 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) and T Rowe Price Media and Telecomm ( PRMTX). 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) and Vanguard Mega Cap 300 Gr Index I ( VMGAX). 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.