497 1 form.htm

Federated MDT Series

Federated MDT All Cap Core Fund
Federated MDT Balanced Fund
Federated MDT Large Cap Growth Fund
Federated MDT Small Cap Core Fund
Federated MDT Small Cap Growth Fund

Federated MDT Stock Trust

CLASS A SHARES
CLASS C SHARES
CLASS K SHARES
INSTITUTIONAL SHARES
INSTITUTIONAL SERVICE SHARES

SUPPLEMENT TO current pROSPECTUSES

1. In the Prospectus for Federated MDT Stock Trust, under the heading entitled, “Fund Summary Information,” in the sub-section entitled, Fund Management, please delete all references to Douglas K. Thunen in their entirety and add the following:

“David A. Troiano joined the Investment Team in 2006. As a Research Manager, he is responsible for ongoing evaluation and enhancement of the Optimum Q Process, including software code design and development. Previously, Mr. Troiano served as a software design engineer with Microsoft Corporation from August 2004 to November 2006. He received his A.B., Magna Cum Laude, Computer Science, from Harvard College.”

2. In each above listed Fund's Prospectus, under the heading entitled, “Who Manages the Fund?,” in the sub-section entitled, Portfolio Management Information, please delete all references to Douglas K. Thunen in their entirety. In addition, please delete the second paragraph in its entity and replace with the following:

“Effective August 2008, key members of the Investment Team, Daniel J. Mahr, Frederick L. Konopka and Brian M. Greenberg, have been named Portfolio Managers of the Fund as they continue their work with the Optimum Q Process. David A. Troiano was named a Portfolio Manager of the Fund in June 2010.”

Finally, please add the following as the final paragraph:

June 29, 2010

Federated Investors Funds
4000 Ericsson Drive
Warrendale, PA 15086-7561

Federated Securities Corp., Distributor

Q450634 (6/10)

Federated MDT Series

Federated MDT All Cap Core Fund
Federated MDT Balanced Fund
Federated MDT Large Cap Growth Fund
Federated MDT Small Cap Core Fund
Federated MDT Small Cap Growth Fund

Federated MDT Stock Trust

CLASS A SHARES
CLASS C SHARES
CLASS K SHARES
INSTITUTIONAL SHARES
INSTITUTIONAL SERVICE SHARES

SUPPLEMENT TO current Statements of Additional Information

In the Statements of Additional Information, under the heading entitled, “Who Manages and Provides Services to the Fund?,” in the sub-section entitled, Portfolio Manager Information, please delete all references to Douglas K. Thunen in their entirety and add the following:

Federated MDT All Cap Core Fund

Additional Accounts Managed by David Troiano

Types of Accounts Managed by David Troiano	Total Number of Additional Accounts Managed/Total Assets	Additional Accounts/Assets Managed that are Subject to Advisory Fee Based on Account Performance
Registered Investment Companies	6/$526 million	0
Other Pooled Investment Vehicles	2/$118 million	0
Other Accounts	47/$2,674 million	1/$0.4 million

Dollar value range of shares owned in the Fund: None.

David Troiano is paid a fixed base salary and a variable annual incentive. Base salary is determined within a market competitive position-specific salary range, based on the portfolio manager’s experience and performance. For purposes of calculating the annual incentive amount, each mutual fund and institutional account managed by the Adviser is categorized as reflecting one of several designated “Strategies.” The annual incentive amount is based on current calendar year asset-weighted composite investment performance of each Strategy, which is measured on a total return basis gross of fees and expenses vs. the Strategy’s designated benchmark (i.e., with respect to the Fund’s Strategy, Russell 3000 Index). As noted above, Mr. Troiano is also the portfolio manager for other accounts in addition to the Fund. Such other accounts may be categorized as reflecting different Strategies, which may have different benchmarks. Although the performance of each Strategy composite is considered in calculating the annual incentive amount, their relative weightings differ. The performance of one of the other Strategies (which does not include the Fund in its composite performance) represents a significant portion of the calculation. The remaining Strategies are divided into two groups, with each Strategy within a group receiving equal weighting. The Strategy to which the Fund is assigned and the other Strategies in the same group receive higher weighting than Strategies in the other group. As a separate matter, pursuant to the terms of a business acquisition agreement, Mr. Troiano may receive additional consideration based on the achievement of specified revenue targets.

As a general matter, certain conflicts of interest may arise in connection with a portfolio manager’s management of a fund’s investments, on the one hand, and the investments of other accounts for which the portfolio manager is responsible, on the other. For example, it is possible that the various accounts managed could have different investment strategies that, at times, might conflict with one another to the possible detriment of the Fund. Alternatively, to the extent that the same investment opportunities might be desirable for more than one account, possible conflicts could arise in determining how to allocate them. Other potential conflicts might include conflicts created by specific portfolio manager compensation arrangements, and conflicts relating to selection of brokers or dealers to execute fund portfolio trades and/or specific uses of commissions from Fund portfolio trades (for example, research, or “soft dollars”). The Adviser has structured the portfolio managers’ compensation in a manner, and the Fund has adopted policies and procedures, reasonably designed to safeguard the Fund from being negatively affected as a result of any such potential conflicts.

Federated MDT Balanced Fund

Additional Accounts Managed by David Troiano

Types of Accounts Managed by David Troiano	Total Number of Additional Accounts Managed/Total Assets	Additional Accounts/Assets Managed that are Subject to Advisory Fee Based on Account Performance
Registered Investment Companies	6/$564 million	0
Other Pooled Investment Vehicles	2/$118 million	0
Other Accounts	47/$2,674 million	1/$0.4 million

Dollar value range of shares owned in the Fund: None.

David Troiano is paid a fixed base salary and a variable annual incentive. Base salary is determined within a market competitive position-specific salary range, based on the portfolio manager’s experience and performance. Mr. Troiano manages only the equity portion of the Fund’s portfolio. For purposes of calculating the annual incentive amount, each mutual fund and institutional account managed by the Adviser is categorized as reflecting one of several designated “Strategies.” The annual incentive amount is based on current calendar year asset-weighted composite investment performance of each Strategy, which is measured on a total return basis gross of fees and expenses vs. the Strategy’s designated benchmark (i.e., with respect to the Fund’s Strategy, 60% S&P 500 Index, 40% Barclays Capital U.S. Aggregate Bond Index). As noted above, Mr. Troiano is also the portfolio manager for other accounts in addition to the Fund. Such other accounts may be categorized as reflecting different Strategies, which may have different benchmarks. Although the performance of each Strategy composite is considered in calculating the annual incentive amount, their relative weightings differ. The performance of the Strategy to which the Fund is assigned represents a significant portion of the calculation. The remaining Strategies are divided into two groups, with each Strategy within a group receiving equal weighting. As a separate matter, pursuant to the terms of a business acquisition agreement, Mr. Troiano may receive additional consideration based on the achievement of specified revenue targets.

Federated MDT Large Cap Growth Fund

Additional Accounts Managed by David Troiano

Types of Accounts Managed by David Troiano	Total Number of Additional Accounts Managed/Total Assets	Additional Accounts/Assets Managed that are Subject to Advisory Fee Based on Account Performance
Registered Investment Companies	6/$608 million	0
Other Pooled Investment Vehicles	2/$118 million	0
Other Accounts	47/$2,674 million	1/$0.4 million

Dollar value range of shares owned in the Fund: None.

David Troiano is paid a fixed base salary and a variable annual incentive. Base salary is determined within a market competitive position-specific salary range, based on the portfolio manager’s experience and performance. For purposes of calculating the annual incentive amount, each mutual fund and institutional account managed by the Adviser is categorized as reflecting one of several designated “Strategies.” The annual incentive amount is based on current calendar year asset-weighted composite investment performance of each Strategy, which is measured on a total return basis gross of fees and expenses vs. the Strategy’s designated benchmark (i.e., with respect to the Fund’s Strategy, Russell 1000 Growth Index). As noted above, Mr. Troiano is also the portfolio manager for other accounts in addition to the Fund. Such other accounts may be categorized as reflecting different Strategies, which may have different benchmarks. Although the performance of each Strategy composite is considered in calculating the annual incentive amount, their relative weightings differ. The performance of one of the other Strategies (which does not include the Fund in its composite performance) represents a significant portion of the calculation. The remaining Strategies are divided into two groups, with each Strategy within a group receiving equal weighting. The Strategy to which the Fund is assigned and the other Strategies in the same group receive lower weighting than Strategies in the other group. As a separate matter, pursuant to the terms of a business acquisition agreement, Mr. Troiano may receive additional consideration based on the achievement of specified revenue targets.

Federated MDT Small Cap Core Fund

Additional Accounts Managed by David Troiano

Types of Accounts Managed by David Troiano	Total Number of Additional Accounts Managed/Total Assets	Additional Accounts/Assets Managed that are Subject to Advisory Fee Based on Account Performance
Registered Investment Companies	6/$663 million	0
Other Pooled Investment Vehicles	2/$118 million	0
Other Accounts	47/$2,674 million	1/$0.4 million

Dollar value range of shares owned in the Fund: None.

David Troiano is paid a fixed base salary and a variable annual incentive. Base salary is determined within a market competitive position-specific salary range, based on the portfolio manager’s experience and performance. For purposes of calculating the annual incentive amount, each mutual fund and institutional account managed by the Adviser is categorized as reflecting one of several designated “Strategies.” The annual incentive amount is based on current calendar year asset-weighted composite investment performance of each Strategy, which is measured on a total return basis gross of fees and expenses vs. the Strategy’s designated benchmark (i.e., with respect to the Fund’s Strategy, Russell 2000 Index). As noted above, Mr. Troiano is also the portfolio manager for other accounts in addition to the Fund. Such other accounts may be categorized as reflecting different Strategies, which may have different benchmarks. Although the performance of each Strategy composite is considered in calculating the annual incentive amount, their relative weightings differ. The performance of one of the other Strategies (which does not include the Fund in its composite performance) represents a significant portion of the calculation. The remaining Strategies are divided into two groups, with each Strategy within a group receiving equal weighting. The Strategy to which the Fund is assigned and the other Strategies in the same group receive higher weighting than Strategies in the other group. As a separate matter, pursuant to the terms of a business acquisition agreement, Mr. Troiano may receive additional consideration based on the achievement of specified revenue targets.

Federated MDT Small Cap Growth Fund

Additional Accounts Managed by David Troiano

Types of Accounts Managed by David Troiano	Total Number of Additional Accounts Managed/Total Assets	Additional Accounts/Assets Managed that are Subject to Advisory Fee Based on Account Performance
Registered Investment Companies	6/$620 million	0
Other Pooled Investment Vehicles	2/$118 million	0
Other Accounts	47/$2,674 million	1/$0.4 million

Dollar value range of shares owned in the Fund: None.

David Troiano is paid a fixed base salary and a variable annual incentive. Base salary is determined within a market competitive position-specific salary range, based on the portfolio manager’s experience and performance. For purposes of calculating the annual incentive amount, each mutual fund and institutional account managed by the Adviser is categorized as reflecting one of several designated “Strategies.” The annual incentive amount is based on current calendar year asset-weighted composite investment performance of each Strategy, which is measured on a total return basis gross of fees and expenses vs. the Strategy’s designated benchmark (i.e., with respect to the Fund’s Strategy, Russell 2000 Growth Index). As noted above, Mr. Troiano is also the portfolio manager for other accounts in addition to the Fund. Such other accounts may be categorized as reflecting different Strategies, which may have different benchmarks. Although the performance of each Strategy composite is considered in calculating the annual incentive amount, their relative weightings differ. The performance of one of the other Strategies (which does not include the Fund in its composite performance) represents a significant portion of the calculation. The remaining Strategies are divided into two groups, with each Strategy within a group receiving equal weighting. The Strategy to which the Fund is assigned and the other Strategies in the same group receive higher weighting than Strategies in the other group. As a separate matter, pursuant to the terms of a business acquisition agreement, Mr. Troiano may receive additional consideration based on the achievement of specified revenue targets.

more than one account, possible conflicts could arise in determining how to allocate them. Other potential conflicts might include conflicts created by specific portfolio manager compensation arrangements, and conflicts relating to selection of brokers or dealers to execute fund portfolio trades and/or specific uses of commissions from Fund portfolio trades (for example, research, or “soft dollars”). The Adviser has structured the portfolio managers’ compensation in a manner, and the Fund has adopted policies and procedures, reasonably designed to safeguard the Fund from being negatively affected as a result of any such potential conflicts.

Federated MDT Stock Trust

Additional Accounts Managed by David Troiano

Types of Accounts Managed by David Troiano	Total Number of Additional Accounts Managed/Total Assets	Additional Accounts/Assets Managed that are Subject to Advisory Fee Based on Account Performance
Registered Investment Companies	6/$440 million	0
Other Pooled Investment Vehicles	2/$118 million	0
Other Accounts	47/$2,674 million	1/$0.4 million

Dollar value range of shares owned in the Fund: None.

David Troiano is paid a fixed base salary and a variable annual incentive. Base salary is determined within a market competitive position-specific salary range, based on the portfolio manager’s experience and performance. For purposes of calculating the annual incentive amount, each mutual fund and institutional account managed by the Adviser is categorized as reflecting one of several designated “Strategies.” The annual incentive amount is based on current calendar year asset-weighted composite investment performance of each Strategy, which is measured on a total return basis gross of fees and expenses vs. the Strategy’s designated benchmark (i.e., with respect to the Fund’s Strategy, Russell 1000 Value Index). As noted above, Mr. Troiano is also the portfolio manager for other accounts in addition to the Fund. Such other accounts may be categorized as reflecting different Strategies, which may have different benchmarks. Although the performance of each Strategy composite is considered in calculating the annual incentive amount, their relative weightings differ. The performance of one of the other Strategies (which does not include the Fund in its composite performance) represents a significant portion of the calculation. The remaining Strategies are divided into two groups, with each Strategy within a group receiving equal weighting. The Strategy to which the Fund is assigned and the other Strategies in the same group receive lower weighting than Strategies in the other group. As a separate matter, pursuant to the terms of a business acquisition agreement, Mr. Troiano may receive additional consideration based on the achievement of specified revenue targets.

June 29, 2010

Federated Investors Funds
4000 Ericsson Drive
Warrendale, PA 15086-7561

Federated Securities Corp., Distributor

Q450633 (6/10)