## Saturna Sustainable  Bond Fund

**Ticker Symbol: SEBFX**

**March 29, 2016**

### SUMMARY PROSPECTUS

Before you invest, you may want to review Saturna Sustainable Bond Fund's prospectus, which contains moreinformation about the Fund and its risks. You can find the Fund's **prospectus** and other information about theFund, including the **statement of additional information** and most recent reports to shareowners, online atwww.saturnasustainable.com/prospectus. You can also get this information at no cost by calling 1-800-728-8762or by sending an email request to info@saturna.com. The Fund's prospectus and statement of additionalinformation, both dated March 29, 2016, are incorporated by reference into this Summary Prospectus.

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| Saturna Sustainable Bond Fund | SEBFX |
|-------------------------------|-------|

### Investment Objective

Current income and capital preservation.

### Fees and Expenses

**Shareowner Fees**

There are no fees that shareowners pay directly from their investments, such as charges for purchases, redemptions, and exchanges of shares.

| **Annual Fund Operating Expenses** (expenses that you pay each year as a percentage of the value of your investment) |
|----------------------------------------------------------------------------------------------------------------------|
| Management Fees                                                                                                      | 0.55% |
| Distribution (12b-1) Fees                                                                                            | 0.25% |
| Other Expenses¹                                                                                                 | 0.22% |
| Total Annual Fund Operating Expenses                                                                                 | 1.02% |
| Fee Waiver and Expense Reimbursement                                                                                 | 0.13% |
| Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement²                                | 0.89% |

¹ The "Other Expenses" are based on estimated amounts for the initial fiscal year.

² The investment adviser has committed through March 31, 2017, to waive fees and/or reimburse expenses to the extent necessary to ensure that the Fund's net operating expenses, excluding brokerage commissions, interest, taxes, and extraordinary expenses do not exceed the net operating expense ratio of 0.89%. This expense limitation agreement may be changed or terminated only with approval of the Board of Trustees.

**Example**

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. 

The Example assumes you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same. Although actual costs may be higher or lower, based on these assumptions, your costs would be:

| 1 year | 3 years | 5 years | 10 years |
|--------|---------|---------|----------|
| $104   | $325    | $563    | $1,248   |

**Portfolio Turnover**

The Fund may have transaction costs, such as commissions and a bid-ask spread, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the example, affect your after-tax returns. During the most recent fiscal year, the Fund's portfolio turnover rate was 4.27% of the average value of its portfolio.

### Principal Investment Strategies

Under normal conditions, the Fund invests at least 80% of its assets in bonds of issuers located throughout the world that the Fund's adviser believes demonstrate sustainable characteristics. For purposes of this investment policy, the Fund's adviser considers issuers with sustainable characteristics to be those issuers that are generally larger, more established, consistently profitable, and financially strong, and with low risks in the areas of the environment, social responsibility, and corporate governance ("ESG"). The Fund's adviser uses an internally developed ESG rating system to identify issuers that the Fund's adviser believes present low ESG risks. 

Under normal conditions, the Fund invests at least 65% of its assets in bonds within the four highest grades (Aaa, Aa, A, or Baa) and may invest up to 35% in unrated and high-yield bonds.

### Principal Risks of Investing

**Market risk:** The value of the Fund's shares rises and falls as the market value of the securities in which the Fund invests goes up and down. The market value of securities will fluctuate, sometimes significantly and unpredictably, with stocks generally being more volatile than bonds. When you redeem your shares, they may be worth more or less than what you paid for them. Only consider investing in the Fund if you are willing to accept the risk that you may lose money.

**Investment strategy risk:** The adviser believes that sustainable investing may mitigate security-specific risk, but the screens used in connection with sustainable investing reduces the investable universe, which limits opportunities and may increase the risk of loss during market declines. In addition, the Fund has a relatively limited operating history, having commenced investment operations in March 2015, and its limited performance history does not provide extensive information on how the Funds may perform in different market conditions. 

**Interest rate risk:** Investing in bonds includes the risk that as interest rates rise, bond prices will fall. Conversely, during periods of declining interest rates bond prices generally rise, but bond issuers may call or prepay the bond and reissue debt at lowe rinterest rates. The longer a bond's maturity, the more sensitive the bond is to interest rate changes.

**Credit risk:** Investing in bonds includes the risk that an issuer will not pay interest or principal when due, or the issuer may default altogether. If an issuer's credit quality is perceived to decline, the value and liquidity of the issuer's bonds may also decline.

| Saturna Sustainable Bond Fund | SEBFX |
|-------------------------------|-------|

**High yield risk:** Investing in bonds that are unrated or rated below investment grade, which are known as "junk bonds" typically offer higher yields to compensate investors for increased credit risk. Issuers of high-yield securities generally are not as strong financially and are more vulnerable to changes that could affect their ability to make interest and principal payments. High-yield securities generally are more volatile and less liquid (harder to sell), which may make such securities more difficult to value.

**Foreign investing risk:** Foreign investing involves risks not normally associated with US securities. These risks include fluctuations in currency exchange rates, less public information about securities, less governmental market supervision, and lack of uniform financial, social, and political standards. Foreign investing heightens the risk of confiscatory taxation, seizure or nationalization of assets, currency controls, or adverse political or social developments that affect investments.

**Liquidity risk:** Liquidity risk exists when particular investments are difficult to sell and may be more difficult to value. If the Fund is forced to sell these investments during unfavorable conditions to meet redemptions or for other cash needs, the Fund may lose money on its investments. As a result, the Fund may be unable to achieve its objective.

### Performance

This Prospectus does not show performance of the Fund because the Fund has not completed one full calendar year of operations as of the date of this prospectus. Future reports will show how the Fund's average annual total returns for the required time periods compare with the Citi World BIG Bond Index.

Performance of the Fund, which provides some indication of the risks of investing in the Fund, will vary from year to year.

### Investment Adviser

Saturna Capital Corporation is the Fund's investment adviser.

### Portfolio Manager

Mr. Patrick Drum MBA, CFA, is the person primarily responsible for the day-to-day management of the Saturna Sustainable Bond Fund. Mr. Bryce Fegley CFA, is the deputy portfolio manager. They have been the managers of the Fund since 2015, the Fund's inception.

### Purchase and Sale of Fund Shares

You may open an account and purchase shares by sending a completed application, a photocopy of a government-issued identity document, and a check for $10,000 or more ($100 for an IRA or retirement plan) payable to the Saturna Sustainable Bond Fund. Shareowners may purchase additional shares at any time in minimum amounts of $25.

Shareowners may redeem shares on any business day by several methods:

**Written request**

> 
Write: Sextant Mutual Funds          Box N          Bellingham, WA 98227-0596

Or Fax: 360-734-0755

**Telephone request**

> 
Call: 800-728-8762 or 360-734-9900

### Tax Information

Any distributions you receive from the Fund may be taxed as ordinary income, qualified dividend income, or capital gains.

### Financial Intermediary Compensation

If you purchase the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies may pay the intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your financial intermediary's website for more information.

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