The Week's Best and Worst Mutual Funds

It's crucial for investors to be in the best-performing mutual funds to suit their investment strategies. TheStreet.com Ratings analyzes mutual funds by investment classes so investors know which ones are performing well -- and which are not.

Below is our recap of the best and worst performers in a variety of open-end mutual fund classifications for the week ending Oct. 4. All total-return figures and stock-price movements were computed over that Wednesday-to-Wednesday period.

Large-Cap

The top-performing large-cap fund was the (AMDEX Quote)Amidex35 Israel Mutual Fund (AMDEX), which grew 2.9%. Its top holding, Teva Pharmaceuticals (TEVA Quote), advanced 2.8%. With a drubbing of 5.8% for the (TAGRX Quote)John Hancock Large-Cap Equity Fund's (TAGRX) largest position of British Energy Group(BGY Quote) on the recent reversal in energy prices, the fund lost 2.4% of its value.

Mid-Cap

The (AFMAX Quote)AFBA 5Star Mid Cap Fund (AFMAX) rose 2.2%; its largest holding, Checkfree (CKFR Quote), moved up 2.1%. The (ADJEX Quote)Azzad Ethical Mid-Cap Fund (ADJEX) fared less well, down 1.3%, as holding Questar (STR Quote) gave up 2.1%.

Small-Cap

The (BUFSX Quote)Buffalo Small-Cap Fund (BUFSX) improved by 2.2%, bolstered by a 4.4% bump in WMS Industries (WMS Quote). On the downside, (ASTRX Quote)Ameritor Security Trust Fund (ASTRX) slid 2.7% as its position in Canada's Northern Dynasty Minerals(NDM Quote) was cut by 11.3%.

Aggressive Growth

Insider buying by a Goodrich (GR Quote) director added 2.2% to the stock and 2.1% to the (HCMAX Quote)Hillman Focused Advantage Fund (HCMAX). The (NCAPX Quote)New Century Opportunistic Portfolio (NCAPX), a fund of funds, slipped 1.4% as its largest fund holding, iShares Goldman Sachs Natural Resources Index Fund(IGE Quote), gave back 3.4%.