One Stop Systems (OSS) 424B5 Prospectus supplement for primary offering

Filed pursuant to Rule 424(b)(5)
Registration No. 333-231513

PROSPECTUS SUPPLEMENT

(To Prospectus dated May 15, 2019)

$10,000,000

Common Stock

We have entered into an Equity Distribution Agreement with Noble Capital Markets, Inc., a Florida corporation (“Noble”) dated as of June 26, 2019 relating to our common stock, par value $0.0001 per share, offered by this prospectus supplement and the accompanying prospectus. Under this prospectus supplement we may offer and sell our common stock having an aggregate offering price of up to $10,000,000 through Noble, acting as our agent.

Our common stock is listed on Nasdaq and trades under the symbol “OSS.” On June 5, 2019, the last reported sale price of our common stock was $1.70 per share.

The aggregate market value of our outstanding common stock held bynon-affiliates was approximately $14.5 million, which was calculated based on 8,508,675 shares of outstanding common stock held bynon-affiliates as of June 5, 2019, and a price per share of $1.70, the closing price of our common stock on June 5, 2019. Pursuant to General Instruction I.B.6 of FormS-3, in no event will we sell securities pursuant to this registration statement with a value more thanone-third of the aggregate market value of our common stock held bynon-affiliates in any12-month period, so long as the aggregate market value of our common stock held bynon-affiliates is less than $75.0 million. In the event that subsequent to the effective date of this registration statement, the aggregate market value of our outstanding common stock held bynon-affiliates equals or exceeds $75.0 million, then theone-third limitation on sales shall not apply to additional sales made pursuant to this registration statement. We have not sold any securities pursuant to General Instruction I.B.6 of FormS-3 during the 12 calendar months prior to, and including, the date of this registration statement.

Sales of shares of our common stock, if any, under this prospectus supplement and the accompanying prospectus may be made by any method that is deemed an “at the market offering” as defined in Rule 415 promulgated under the Securities Act of 1933, as amended, including sales made directly on or through the Nasdaq Capital Market (the “Nasdaq”), the existing trading market for our common shares. Noble is not required to sell any specific number of dollar amount of securities, but will act as sales agent using commercially reasonable efforts consistent with its normal trading and sales practices, on mutually agreed terms between Noble and us. There is no arrangement for funds to be received in any escrow, trust or similar arrangement.

Noble will be entitled to compensation under the terms of the Equity Distribution Agreement at a commission rate equal to 3.0% of the gross proceeds per share sold, except as otherwise provided therein. See “Plan of Distribution” beginning on pageS-11 for additional information regarding the compensation paid to Noble. In connection with the sale of common stock on our behalf, Noble may be deemed to be an “underwriter” within the meaning of the Securities Act, and the compensation of Noble may be deemed to be underwriting commissions or discounts. We have also agreed to provide indemnification and contribution to Noble against certain liabilities, including liabilities under the Securities Act.

We are an “emerging growth company” as that term is used in the Jumpstart Our Business Startups Act of 2012 and, as such, have elected to comply with certain reduced public company reporting requirements for this prospectus and future filings.

Investing in our securities involves a high degree of risk. Before buying shares of our common stock, you should carefully consider the risk factors described in “Risk Factors” beginning on pageS-7 of this prospectus supplement and in any documents incorporated by reference into this prospectus supplement.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities, or determined if this prospectus supplement and the accompanying prospectus is accurate or complete. Any representation to the contrary is a criminal offense.

Noble Capital Markets

The date of this prospectus supplement is June 26, 2019.

TABLE OF CONTENTS

Prospectus Supplement

	PAGE
ABOUT THIS PROSPECTUS SUPPLEMENT		S-1
CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS		S-2
PROSPECTUS SUPPLEMENT SUMMARY		S-3
THE OFFERING		S-6
RISK FACTORS		S-7
USE OF PROCEEDS		S-8
DILUTION		S-9
DESCRIPTION OF COMMON STOCK		S-10
PLAN OF DISTRIBUTION		S-11
LEGAL MATTERS		S-12
EXPERTS		S-12
WHERE YOU CAN FIND MORE INFORMATION		S-12
INCORPORATION OF INFORMATION BY REFERENCE		S-13

Prospectus

	PAGE
ABOUT THIS PROSPECTUS		1
PROSPECTUS SUMMARY		2
RISK FACTORS		7
FORWARD-LOOKING STATEMENTS		8
WHERE YOU CAN FIND MORE INFORMATION		9
INCORPORATION OF INFORMATION BY REFERENCE		10
USE OF PROCEEDS		11
PLAN OF DISTRIBUTION		12
DESCRIPTION OF CAPITAL STOCK		14
DESCRIPTION OF DEBT SECURITIES		19
DESCRIPTION OF WARRANTS		26
DESCRIPTION OF SUBSCRIPTION RIGHTS		28
DESCRIPTION OF UNITS		29
LEGAL MATTERS		29
EXPERTS		29

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ABOUT THIS PROSPECTUS SUPPLEMENT

This prospectus supplement is a supplement to the accompanying prospectus that is also a part of this document. This prospectus supplement and the accompanying prospectus, dated June 26, 2019, are part of a registration statement on FormS-3 (File No.333-231513) that we filed with the Securities and Exchange Commission (the “SEC”), utilizing a “shelf” registration process. Under the shelf registration process, we may offer and sell from time to time in one or more offerings the securities described in the accompanying prospectus.

This document is in two parts. The first part is this prospectus supplement, which describes the securities we are offering and the terms of the offering and also adds to and updates information contained in the accompanying prospectus and the documents incorporated by reference into the accompanying prospectus. The second part is the accompanying prospectus, which provides more general information, some of which may not apply to the securities offered by this prospectus supplement. Generally, when we refer to this “prospectus,” we are referring to both documents combined. To the extent there is a conflict between the information contained in this prospectus supplement, on the one hand, and the information contained in the accompanying prospectus or any document incorporated by reference therein, on the other hand, you should rely on the information in this prospectus supplement. We urge you to carefully read this prospectus supplement and the accompanying prospectus and any related free writing prospectus, together with the information incorporated herein and therein by reference as described under the heading “Incorporation of Information by Reference,” before buying any of the securities being offered.

You should rely only on the information that we have provided or incorporated by reference in this prospectus supplement and the accompanying prospectus and any related free writing prospectus that we may authorize to be provided to you. We have not, and Noble has not, authorized anyone to provide you with different information. No other dealer, salesperson or other person is authorized to give any information or to represent anything not contained in this prospectus supplement and the accompanying prospectus or any related free writing prospectus that we may authorize to be provided to you. You must not rely on any unauthorized information or representation. This prospectus supplement is an offer to sell only the securities offered hereby and only under circumstances and in jurisdictions where it is lawful to do so. You should assume that the information in this prospectus supplement and the accompanying prospectus or any related free writing prospectus is accurate only as of the date on the front of the document and that any information we have incorporated by reference is accurate only as of the date of the document incorporated by reference, regardless of the time of delivery of this prospectus supplement and the accompanying prospectus or any related free writing prospectus, or any sale of a security.

This prospectus supplement contains summaries of certain provisions contained in some of the documents described herein, but reference is made to the actual documents for complete information. All of the summaries are qualified in their entirety by the actual documents. Copies of some of the documents referred to herein have been filed, will be filed or will be incorporated by reference as exhibits to the registration statement of which this prospectus supplement is a part, and you may obtain copies of those documents as described below under the heading “Where You Can Find More Information.”

As used in this prospectus supplement, the terms “we”, “us”, “our”, “Company”, “OSS” and “One Stop” refer to One Stop Systems, Inc., a Delaware corporation.

We own or have rights to trademarks or trade names that we use in conjunction with the operation of our business. Each trademark, trade name or service mark of any other company appearing in this prospectus supplement or the accompanying prospectus belongs to its holder. Use or display by us of other parties’ trademarks, trade names or service marks is not intended to and does not imply a relationship with, or endorsement or sponsorship by us of, the trademark, trade name or service mark owner.

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The industry and market data contained or incorporated by reference in this prospectus supplement are based either on our management’s own estimates or on independent industry publications, reports by market research firms or other published independent sources. Although we believe these sources are reliable, we have not independently verified the information and cannot guarantee its accuracy and completeness, as industry and market data are subject to change and cannot always be verified with complete certainty due to limits on the availability and reliability of raw data, the voluntary nature of the data gathering process and other limitations and uncertainties inherent in any statistical survey of market shares. Accordingly, you should be aware that the industry and market data contained or incorporated by reference in this prospectus supplement, and estimates and beliefs based on such data, may not be reliable. Unless otherwise indicated, all information contained or incorporated by reference in this prospectus supplement concerning our industry in general or any segment thereof, including information regarding our general expectations and market opportunity, is based on management’s estimates using internal data, data from industry related publications, consumer research and marketing studies and other externally obtained data.

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus supplement, the accompanying prospectus, and documents incorporated herein by reference contain “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements involve a number of risks and uncertainties. We caution readers that any forward-looking statement is not a guarantee of future performance and that actual results could differ materially from those contained in the forward-looking statement. These statements are based on current expectations of future events. Such statements include, but are not limited to, statements about future financial and operating results, plans, objectives, expectations and intentions, costs and expenses, interest rates, outcome of contingencies, financial condition, results of operations, liquidity, cost savings, objectives of management, business strategies, debt financing, clinical trial timing and plans, the achievement of clinical and commercial milestones, the advancement of our technologies and our product candidates, and other statements that are not historical facts. You can find many of these statements by looking for words like “believes,” “expects,” “anticipates,” “estimates,” “may,” “might,” “should,” “will,” “could,” “plan,” “intend,” “project,” “seek” or similar expressions in this prospectus supplement, the accompanying prospectus, or in documents incorporated by reference into this prospectus supplement. We intend that such forward-looking statements be subject to the safe harbors created thereby.

These forward-looking statements are based on the current beliefs and expectations of our management and are subject to significant risks and uncertainties. If underlying assumptions prove inaccurate or unknown risks or uncertainties materialize, actual results may differ materially from current expectations and projections. Factors that might cause such a difference include those discussed in Part I, Item 1A “Risk Factors” in our Annual Report onForm 10-K for the fiscal year ended December 31, 2018, as well as those discussed in this prospectus supplement, the accompanying prospectus, and in the documents incorporated by reference into this prospectus supplement. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this prospectus supplement or, in the case of documents referred to or incorporated by reference, the date of those documents.

All subsequent written or oral forward-looking statements attributable to us or any person acting on our behalf are expressly qualified in their entirety by the cautionary statements contained or referred to in this section. We do not undertake any obligation to release publicly any revisions to these forward-looking statements to reflect events or circumstances after the date of this prospectus supplement or to reflect the occurrence of unanticipated events, except as may be required under applicable U.S. securities law. If we do update one or more forward-looking statements, no inference should be drawn that we will make additional updates with respect to those or other forward-looking statements.

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PROSPECTUS SUPPLEMENT SUMMARY

This summary description about us and our business highlights selected information contained elsewhere in, or incorporated by reference into, this prospectus supplement and the accompanying prospectus. It does not contain all the information you should consider before investing in our common stock. Before making an investment decision, you should read carefully this prospectus supplement and the accompanying prospectus, including, without limitation, the “Risk Factors” beginning on pageS-7 of this prospectus supplement, and any other offering materials, together with the additional information described under the captions “Where You Can Find More Information” and “Incorporation of Information By Reference,” beginning on pageS-12 of this prospectus supplement.

Our Company

One Stop Systems, Inc. (“OSS”) designs and manufactures high-speed computing systems for high performance computing (“HPC”) applications that require fast processing and storage of large information data sets. These applications include artificial intelligence (“AI”), machine learning, seismic exploration, security and defense. Drawing upon years of expertise in designing and manufacturing custom systems for original equipment manufacturers (“OEMs”), our systems are built using the latest graphical processing unit (“GPU”) and flash-based solid-state drive (“SSD”) storage technologies.

We first began designing and manufacturing custom systems for defense, manufacturing, and telecom customers in 1998 and have always strived to be a leading innovator in our space. When PCI Express (“PCIe”) – the maincomponent-to-component interconnect used in all computers today – was introduced by Intel Corporation in 2005, OSS was the first manufacturer to design and produce PCIebox-to-box interconnection products. Today, we believe we have grown to become one of the largest providers of PCIe adapters and expansion systems used worldwide. When GPU technology and flash-based SSD were first introduced to the market, we began designing systems that maximized the power of these technologies. We now produce computer systems with large numbers of GPU cards and SSDs that allow progressively faster processing capabilities. The more GPUs and flash storage available to a server, the faster it can process, store and retrieve data, resulting in time savings and lower cost in running applications. Military video imaging applications are a prime example of mission-critical use of this technology where the ability to quickly and accurately identify battlefield parameters is paramount. We leverage strong relationships with our market-leading customers and suppliers to position ourselves at the forefront of these industries.

We design, assemble and supply systems that attach to both existing servers through PCIe and systems that have servers included. These systems can be clustered together to create powerful “massive computing” engines that occupy less space and require less power and cooling than conventional systems. We also sell software used to operate large 100% SSD storage systems for defense systems and commercial applications.

OSS sells its products worldwide to industry leading companies like Cisco, disguise (formerly d3), National Instruments, Northrop Grumman, Oracle and Raytheon. We are a strategic partner to technology leaders that include NVIDIA, Intel, Western Digital, and Broadcom. We are investing in new market segments adjacent to our core product lines, including development of HPC storage management software and HPC cloud services. We anticipate continued growth in our target markets, and believe we can increase market share through technology leadership, engineering expertise, supply chain management and product innovation.

Industry Background

The worldwide HPC market is expected to grow from $35.6 billion in 2016 to $43.9 billion by 2021, representing a compound annual growth rate (“CAGR”) of 4.3%, according to Intersect 360 Research. We believe we are uniquely positioned as a leading provider of HPC servers, compute accelerators and flash storage arrays to thehigh-end of this growing marketplace.

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HPC applications require significant computing capabilities to analyze large amounts of data quickly, and store and retrieve that data as necessary. Companies, financial institutions, governmental agencies and academic institutions are increasingly turning to HPC solutions to analyze vast amounts of data, and more quickly gain meaningful and actionable insights. Two key technologies, GPUs and SSDs, enable our systems to process and store data more efficiently than traditional systems. By harnessing significant quantities of these components, companies can process large volumes of data much more quickly and efficiently.

While traditionally used to drive display applications, today’s advanced GPUs have developed more powerful capabilities fornon-graphical data processing beyond that of typical CPUs (central processing units) that power computer motherboards. In fact, the capabilities and speed ofGPU-accelerated computers are now driving significant advances in AI and machine learning. Vast amounts of data are being collected by internet searches, cameras, sensors and other data generating activities and GPUs can more quickly process sophisticated algorithms that can analyze this “Big Data” and reveal unique patterns that lead to new insights and knowledge.

AI and machine learning have begun to transform businesses worldwide, as these advances in computing speed and power come together to enable businesses to solve complex problems. Until recently, many of these algorithms would take weeks or months to produce results. In many cases, the necessary computing capabilities were so expensive, and required so much space and power, they were infeasible. This is where OSS comes in. By accelerating thestate-of-the-art in terms of computing performance, high density (less space) and power efficiency, OSS enables HPC applications to produce results in minutes versus hours or days versus months. In this way, OSS is enabling new data-intensive applications and computational solutions that were previously considered impractical or impossible.

Our Core Strengths and Solutions

Over nearly 20 years, OSS has developed unique expertise and core competencies across the fundamental technologies of today’s rapidly expanding HPC marketplace. These valuable assets are embedded in our leading-edge engineering capabilities, the proprietaryknow-how contained in our extensive library of designs, and brand equity from our reputation as a high quality producer ofstate-of-the-art custom and standard solutions across an array of markets. Our strengths lie in three core areas: high-speed system interconnect design, high-density system design, and storage management software.

High-Speed System Interconnect Design

Members of our technical team are experts in high-speed digital signaling design, particularly regarding PCIe and nvlink signaling. We specialize in the design and production ofstate-of-the-art systems that incorporate the latest high-speed signaling techniques. Our expertise includes circuit design and circuit board layout and routing optimizations, with a focus on achieving the highest levels of signal integrity.

In our current systems, PCIe Gen 3 signals are propagated across multiple circuit boards, connectors and cables, with sufficient signal quality for the receiver to reliably recognize digital signal transitions occurring at 8 billion times per second. However, this is a continually advancing area of technology, and OSS has demonstrated the ability to keep up with the treadmill of technology over several generations of signaling speeds. In fact, we have consistently been among a handful of companies able to come to market first with the latest technology. We delivered the industry’s first PCIe-over-cable solutions for PCIe Gen 1, Gen 2 and Gen 3, and are currently on track to accomplish this again in Gen 4.

In HPC systems, the “need for speed” is constantly driving signaling speeds higher and higher. Our next generation of products that include PCIe Gen 4 and nvlink 2.0 will involve signaling of 16 billion and 20 billion transitions per second, respectively. A diminishing set of companies have the capabilities to design and produce robust, highly reliable systems at these speeds. We believe our core competency in large scale, high-speed design and layout will allow us to remain at the forefront of this growing and ever-evolving industry.

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High-Density System Design

In addition to signal integrity design expertise, we have amassed expertise and proprietaryknow-how in high-density HPC system design. This expertise allows us to develop extremely sophisticated systems that consume less space, weight and power than ever before possible. For multiple reasons, this high-density capability has played a role in our customer design wins.

For military applications, smaller size, weight and power (known as SWaP) is critical in many battlefield systems. One of our more significant recent design wins was for a military aircraft where our solid state storage solution replaced ahard-to-remove,165-pound system with a seven-pound removable module. For solutions contained within data centers, density also plays a significant role. For an equivalent amount of compute power, the OSS solution provided a ten times (10x) reduction in both rack space and power consumption. Economically, this is very compelling, since the cost of data center space and electrical power over the life of the product often exceeds the cost of the computer hardware.

Storage Management Software

On May 9, 2017, OSS entered into an agreement to acquire the source code license for SSD array software known as “Ion” from Western Digital. In connection with the transaction, OSS acquired the software engineering teams that developed the software, with the intent that OSS provide ongoing support to existing Western Digital customers and new releases of the software. This new software team provides OSS with proven expertise that can support the development of SSD storage arrays with exceptional performance, density, reliability and mobility. We expect to leverage this capability with our existing products and services over time.

The Ion software provides an interface to a standard server so it can easily read and write data from an array of SSDs. Two key features set Ion apart from other storage system software products: its optimization forlow-latency, which means an SSD array can return data to the requesting server much more rapidly than those relying upon other types of server software, and Ion’s support for removable andhot-swappable SSD modules that contain multiple SSDs. This feature is essential to applications that require removable and expandable data storage that spans multiple SSDs.

Having an established storage software andin-house software engineering allows OSS to easily produce semi-custom product variations as well as add new features and capabilities to its product portfolio. Future product features may include data encryption,de-duplication and compression, as well as other capabilities requested by our customers.

Our Opportunity

OSS has positioned itself as a technology leader in several key emerging areas of HPC. These include GPU computing, SSD storage arrays and cloud services. These areas are growing rapidly, and each has enormous potential given how they are replacing older technologies in very large markets.

OSS has significant design libraries, expertise and a customer-first approach that enable us to win OEM design and manufacturing business. Since each OEM design win generates revenue streams for3-5 years (and potentially longer for military systems), the business tends to layer new revenue growth with each win. OSS also has a track record of successful strategic mergers and acquisitions, and such future activity could further enhance our growth through the same layering concept.

We believe strong, profitable growth is key to providing increasing shareholder value. We see three key elements driving our growth and profitable outlook. First, many of our existing OEM and military program design-wins are in the early stages of production and we expect them to ramp up significantly. Second, our technology leadership and increasing market presence has supported an increase indesign-win opportunities. Third, an enhanced acquisition capability (due to the additional funding and enhanced liquidity for our stock provided by the initial public offering) will enable us to complete more significant strategic acquisitions that enhance and complement our core strategic capabilities and current growth rate. We will continue to look for opportunities that can be accretive and enhance our overall position.

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THE OFFERING

The following is a brief summary of some of the terms of the offering and is qualified in its entirety by reference to the more detailed information appearing elsewhere in this prospectus supplement and the accompanying base prospectus. For a more complete description of the terms of our common stock, see “Securities We May Offer - Common Stock” in the accompanying base prospectus.

Common stock offered by us	Shares of our common stock having an aggregate offering price of up to $10 million.
Manner of offering	“At the market offering” that may be made from time to time on the Nasdaq or other market for our common stock in the United States through our sales agent, Noble. See the section entitled “Plan of Distribution” of this prospectus supplement.
Sales Agent	Noble Capital Markets, Inc.
Use of proceeds	We intend to use the net proceeds from this offering, if any, for general corporate purposes, which may include funding repayment and refinancing of debt, funding product development, sales and marketing activities, increasing our working capital and acquisitions or investments in businesses, products or technologies that are complementary to our own. Please see the section entitled “Use of Proceeds” in this prospectus supplement.
Nasdaq Capital Market symbol	OSS
Risk Factors	Investing in our securities involves risks. You should carefully consider the risks described under “Risk Factors” in this prospectus supplement, in our most recent Annual Report on Form10-K and our subsequent Quarterly Reports on Form10-Q as well as the other information contained or incorporated by reference in this prospectus supplement and the accompanying prospectus before making a decision to invest in our common stock.

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RISK FACTORS

An investment in our securities involves a high degree of risk. You should carefully consider the specific risks described in our Annual Report on Form10-K for the year ended December 31, 2018 under the heading “Risk Factors” before investing in our securities. You should also consider similar information in any Annual Report on Form10-K and Quarterly Report on Form10-Q or other documents filed by us with the SEC after the date of this prospectus supplement before deciding to invest in our securities. If any of the foregoing risks actually materializes, our business, financial condition, results of operations and prospects could be materially adversely affected. As a result, the value of our securities could decline and you could lose part or all of your investment. The foregoing risks are not the only ones we face. Additional risks and uncertainties not presently known to us or that we currently deem immaterial may also materially affect our business, financial condition, results of operations and prospects. See “Where You Can Find More Information” and “Incorporation of Information By Reference,” beginning on pageS-12 of this prospectus supplement.

Risks Related to this Offering

We will have broad discretion over the use of the net proceeds from this offering, you may not agree with how we use the proceeds and we may not invest the proceeds successfully.

We intend to use the net proceeds, if any, from this offering for general corporate purposes, which may include repayment and refinancing of debt, funding product development, sales and marketing activities, increasing our working capital and acquisitions or investments in businesses, products or technologies that are complementary to our own. Accordingly, we will have broad discretion as to the use of the net proceeds from this offering and could use them for purposes other than those contemplated at the time of this offering. Accordingly, you will be relying on the judgment of our management with regard to the use of these net proceeds, and you will not have the opportunity, as part of your investment decision, to assess whether the proceeds are being used appropriately. It is possible that the proceeds will be invested in a way that does not yield a favorable, or any, return for us.

You will experience immediate dilution in the book value per share of the common stock you purchase.

The offering price per share in this offering may exceed the pro forma net tangible book value per share of our common stock outstanding prior to this offering. Assuming that an aggregate of 5,882,353 shares of our common stock are sold at a price of $1.70 per share, the last reported sale price of our common stock on the Nasdaq Capital Market on June 5, 2019 for aggregate gross proceeds of approximately $10 million, and after deducting commissions and estimated aggregate offering expenses payable by us, you will experience immediate dilution of $0.61 per share, representing the difference between our pro forma net tangible book value per share as of June 5, 2019 and our pro forma as adjusted net tangible book value per share as of June 5, 2019 after giving effect to this offering at the assumed size and offering price. The exercise of outstanding stock options will result in further dilution of your investment. See the section below entitled “Dilution” on pageS-9 for a more detailed discussion of the dilution you will incur in connection with this offering.

You may experience further dilution as a result of future equity offerings.

To raise additional capital, we may in the future offer additional common stock or other securities convertible into or exchangeable for our common stock at prices that may not be the same as the price per share in this offering. We may sell common stock or other securities in any other offering at a price per share that is less than the price per share paid by investors in this offering, and investors purchasing shares or other securities in the future could have rights superior to existing shareholders. The price per share at which we sell additional shares, or securities convertible or exchangeable into our common stock, in future transactions may be higher or lower than the price per share paid by investors in this offering.

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The common stock offered hereby will be sold in “at the market offerings,” and investors who buy shares at different times will likely pay different prices.

Investors who purchase shares in this offering at different times will likely pay different prices, and so may experience different outcomes in their investment results. We will have discretion, subject to market demand, to vary the timing, prices, and numbers of shares sold, and there is no minimum or maximum sales price. Investors may experience a decline in the value of their shares as a result of share sales made at prices lower than the prices they paid.

Because we will not declare cash dividends on our shares of common stock in the foreseeable future, shareholders must rely on appreciation of the value of our common stock for any return on their investment.

We have never declared or paid cash dividends on our common stock. We currently anticipate that we will retain future earnings for the development, operation and expansion of our business and will not declare or pay any cash dividends in the foreseeable future. As a result, only appreciation of the price of our common stock, if any, will provide a return to investors in this offering.

The actual number of shares we will issue under the equity distribution agreement, at any one time or in total, is uncertain.

Subject to certain limitations in the equity distribution agreement with Noble and compliance with applicable law, we have the discretion to deliver placement notices to Noble at any time throughout the term of the equity distribution agreement. The number of shares that are sold by Noble after our delivering a placement notice will fluctuate based on the market price of the common stock during the sales period and limits we set with Noble.

USE OF PROCEEDS

The amount of proceeds from this offering will depend upon the number of shares of our common stock sold and the market prices at which they are sold. We may not be able to sell any shares under or fully utilize the sales agreement with Noble as a source of financing. We intend to use the net proceeds from this offering for general corporate purposes, which may include repayment and refinancing of debt, funding product development, sales and marketing activities, increasing our working capital and acquisitions or investments in businesses, products or technologies that are complementary to our own.

The principal purposes of this offering are to increase our operating and financial flexibility. As of the date of this prospectus supplement, we cannot specify with certainty all of the particular uses for the net proceeds we will have upon completion of this offering. Accordingly, our management will have broad discretion in the application of net proceeds, if any.

DIVIDEND POLICY

We have never declared or paid any cash dividends on our capital stock, and we do not currently intend to pay any cash dividends on our common stock for the foreseeable future. We expect to retain future earnings, if any, to fund the development and growth of our business. Any future determination to pay dividends on our common stock will be at the discretion of our board of directors and will depend upon, among other factors, our results of operations, financial condition, capital requirements and any contractual restrictions.

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DILUTION

If you purchase our common stock in this offering, your interest will be diluted to the extent of the difference between the price per share you pay in this offering and the net tangible book value per share of our common stock after this offering. The net tangible book value of our common stock as of June 5, 2019 was approximately $11.0 million, or approximately $0.76 per share of common stock based upon 14,497,647 shares outstanding. Net tangible book value per share is equal to our total tangible assets, less our total liabilities, divided by the total number of shares of our common stock outstanding as of June 5, 2019.

After giving effect to the sale of our common stock in the aggregate amount of $10,000,000 at an assumed offering price of $1.70 per share, the last reported sale price of our common stock on the Nasdaq on June 5, 2019, and after deducting estimated offering commissions payable by us, our net tangible book value as of June 5, 2019 would have been $20.5 million, or $1.00 per share of common stock. This represents an immediate increase in net tangible book value of $0.24 per share to our existing stockholders and an immediate dilution in net tangible book value of $0.61 per share to new investors in this offering. The following table illustrates this per share dilution:

Assumed public offering price per share			$	1.70
Less transaction costs per share			$	(0.09	)
Net price per share			$	1.61
Net tangible book value (deficit) per share as of June 5, 2019	$	11,006,647
Increase in net tangible book per share attributable to this offering	$	9,500,000
As adjusted net tangible book per share as of June 5, 2019, after giving effect to this offering			$	1.00
Dilution per share to new investors in this offering			$	0.61

The table above assumes for illustrative purposes that an aggregate of 5,882,353 shares of our common stock are sold at a price of $1.70 per share, the last reported sale price of our common stock on the Nasdaq on June 5, 2019, for aggregate gross proceeds of $10,000,000. The shares sold in this offering, if any, will be sold from time to time at various prices.

The number of shares of our common stock to be outstanding immediately after this offering is based on.

The above table and discussion is based on 14,497,647 shares of our common stock outstanding as of June 5, 2019 and excludes the following, all as of June 5, 2019:

• 1,931,349 shares of common stock issuable upon the exercise of stock options and restricted stock units (RSUs) outstanding;

• 965,318 unallocated shares of common stock reserved for future issuance under 2017 Equity Incentive Plan; and

• 630,947 shares of common stock issuable upon exercise of warrants outstanding.

For information regarding the number of shares of our common stock outstanding as of date of this prospectus supplement, including our common stock shares reserved for future issuance, please refer to the following section entitled “Description of Common Stock.”

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DESCRIPTION OF COMMON STOCK

As of the date of the prospectus supplement, we are authorized to issue up to 50,000,000 shares of common stock, $0.0001 par value per share. As of June 5, 2019, 14,497,647 shares of our common stock were issued and outstanding.

Voting Rights

Each share of common stock entitles the holder to one vote with respect to each matter presented to our stockholders on which the holders of common stock are entitled to vote, including the election of directors. Holders of our common stock do not have cumulative voting rights. Except in respect of matters relating to the election and removal of directors on our board of directors and as otherwise provided in our certificate of incorporation or required by law, all matters to be voted on by our stockholders must be approved by a majority of the shares present in person or by proxy at the meeting and entitled to vote on the subject matter. In the case of election of directors, all matters to be voted on by our stockholders must be approved by a plurality of the votes entitled to be cast by all shares of common stock. Accordingly, the holders of a majority of the outstanding shares of common stock entitled to vote in any election of directors can elect all of the directors standing for election, if they so choose, other than any directors that holders of any preferred stock we may issue may be entitled to elect.

Dividends

Subject to preferences that may apply to any shares of preferred stock outstanding at the time, the holders of our common stock will be entitled to share equally, identically and ratably in any dividends that our board of directors may determine to issue from time to time.

Liquidation Rights

In the event of any voluntary or involuntary liquidation, dissolution or winding up of our affairs, holders of our common stock would be entitled to share ratably in our assets that are legally available for distribution to stockholders after payment of our debts and other liabilities. If we have any preferred stock outstanding at such time, holders of the preferred stock may be entitled to distribution and/or liquidation preferences. In either such case, we must pay the applicable distribution to the holders of our preferred stock before we may pay distributions to the holders of our common stock.

Other Rights

Our stockholders have no preemptive, conversion or other rights to subscribe for additional shares, and there are no redemption or sinking funds provisions applicable to the common stock. All outstanding shares are, and all shares offered by this prospectus will be, when sold, validly issued, fully paid and nonassessable. The rights, preferences and privileges of the holders of our common stock will be subject to, and may be adversely affected by, the rights of the holders of shares of any series of our preferred stock that we may designate and issue in the future.

Transfer Agent and Registrar

The transfer agent and registrar for our common stock is Corporate Stock Transfer, Inc. The transfer agent and registrar’s address is 3200 Cherry Creek Drive South, Suite 430, Denver, CO 80209.

Exchange Listing

Our common stock is listed on The Nasdaq Capital Market under the symbol “OSS.”

S-10

PLAN OF DISTRIBUTION

We have entered into an Equity Distribution Agreement (the “Distribution Agreement”), with Noble Capital Markets, Inc., a Florida corporation (“Noble”), pursuant to which we may issue and sell shares of our common stock having aggregate sales proceeds of up to $10 million from time to time through Noble, acting as sales agent. The sales, if any, of common stock made under the Distribution Agreement will be made by any method that is deemed an “at the market offering” as defined in Rule 415 promulgated under the Securities Act, including sales made directly on the Nasdaq, or sales made to or through a market maker other than on an exchange or otherwise. Subject to our prior approval, Noble also may sell the common stock in negotiated transactions at prices prevailing at the time of sale or at prices related to such prevailing market prices. A copy of the Distribution Agreement has been filed as an exhibit to a Current Report on Form8-K and is incorporated by reference into the registration statement of which this prospectus supplement is a part.

Noble will sell the shares of common stock subject to the Distribution Agreement from time to time as agreed upon by us and Noble. Each time we wish to issue and sell shares of common stock, we will notify Noble of the proposed terms of the placement. Once we have so instructed Noble, unless Noble declines to accept the terms of the notice, Noble has agreed to use its commercially reasonable efforts, consistent with its normal trading and sales practices, to sell such shares up to the amount specified on such terms. We may instruct Noble not to sell shares of common stock if the sales cannot be effected at or above the price designated by us in any such instruction. We or Noble may suspend the offering of shares of common stock upon proper notice and subject to other conditions. The obligations of Noble under the Distribution Agreement to sell our common stock are subject to a number of conditions that we must meet.

We will pay Noble a commission for its services in acting as agent in the sale of our common stock pursuant to the Distribution Agreement equal to 3.0% of the gross proceeds we receive from the sales of our common stock, except as otherwise provided in the Distribution Agreement. The remaining sales proceeds, after deducting offering expenses and any transaction fees imposed by any governmental or self-regulatory organization in connection with the sales, will equal our net proceeds for the sale of the shares. We have also agreed to reimburse Noble for its reasonable out of pocket expenses, including legal fees and expenses of counsel, for an aggregate amount not to exceed USD$60,000 (sixty thousand U.S. dollars).

Settlement for sales of common stock will occur on the third business day following the date on which any sales are made in return for payment of the net proceeds to us. There is no arrangement for funds to be received in an escrow, trust or similar arrangement.

In connection with the sale of common stock on our behalf, Noble may, and will with respect to sales effected in an “at the market offering”, be deemed to be an “underwriter” within the meaning of the Securities Act, and the compensation to Noble may be deemed to be underwriting commissions or discounts. We have agreed to provide indemnification and contribution to Noble against certain civil liabilities, including liabilities under the Securities Act.

The offering of our common stock in accordance with the Distribution Agreement will terminate upon the earlier of (1) the sale of all of our shares of common stock subject to the Distribution Agreement, or (2) the termination of the Distribution Agreement as permitted therein.

Noble and its affiliates have provided, and may in the future provide, various investment banking, research, commercial banking, fiduciary and advisory services for us from time to time for which they have received, and may in the future receive, customary fees and expenses. Noble and its affiliates may, from time to time, engage in other transactions with and perform services for us in the ordinary course of their business.

This summary of the material provisions of the Distribution Agreement does not purport to be a complete statement of its terms and conditions. A copy of the Distribution Agreement is filed with the SEC and is incorporated by reference into the registration statement of which this prospectus is a part. See “Where You Can Find More Information” below.

S-11

To the extent required by Regulation M, Noble will not engage in any market making activities involving our common stock while the offering is ongoing under this prospectus.

LEGAL MATTERS

The validity of the securities offered by this prospectus has been passed upon for us by Procopio, Cory, Hargreaves & Savitch, LLP, San Diego, California. Greenberg Traurig, PA, Boca Raton, Florida, is acting as counsel for Noble in connection with this offering.

EXPERTS

The consolidated financial statements of One Stop Systems, Inc. as of December 31, 2018 and 2017, and for each of the years then ended, incorporated by reference in this prospectus supplement, have been so incorporated in reliance on the report of Haskell & White LLP, an independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

WHERE YOU CAN FIND MORE INFORMATION

We have filed with the SEC a registration statement onForm S-3 under the Securities Act with respect to the securities being offered under this prospectus supplement. This prospectus supplement and accompanying prospectus, which forms part of the registration statement, does not contain all of the information in the registration statement. We have omitted certain parts of the registration statement, as permitted by the rules and regulations of the SEC. For further information regarding us and our securities, please see the registration statement and our other filings with the SEC, including our annual, quarterly, and current reports and any proxy statements, which you may read and copy at the Public Reference Room maintained by the SEC at 100 F Street, N.E., Washington, D.C. 20549. You may obtain information about the Public Reference Room by calling the SEC at1-800-SEC-0330. Our public filings with the SEC are also available to the public on the SEC’s Internet website at http://www.sec.gov.

We furnish holders of our common stock with annual reports containing audited financial statements prepared in accordance with accounting principles generally accepted in the United States following the end of each fiscal year. We file reports and other information with the SEC pursuant to the reporting requirements of the Exchange Act. In addition, the reports, proxy statements and other information that we file with the SEC are available to you free of charge through the Investor Relations page of our website, www.onestopsystems.com, as soon as reasonably practicable after they have been electronically filed with, or furnished to, the SEC. We have included our website address as a textual reference and do not intend it as an active link to our website. The contents of our website are not part of this prospectus supplement, and you should not consider the contents of our website in making an investment decision with respect to our securities.

Descriptions in this prospectus supplement and accompanying prospectus of documents are intended to be summaries of the material, relevant portions of those documents, but may not be complete descriptions of those documents. For complete copies of those documents, please refer to the exhibits to the registration statement and other documents filed by us with the SEC.

S-12

INCORPORATION OF INFORMATION BY REFERENCE

The SEC allows us to “incorporate by reference” information that we file with the SEC, which means that we can disclose important information to you by referring you to those other documents. The information incorporated by reference is an important part of this prospectus supplement, and information we file later with the SEC will automatically update and supersede this information. We incorporate by reference the documents listed below and any future filings we make with the SEC under Section 13(a), 13(c), 14, or 15(d) of the Exchange Act prior to the termination of any offering of securities made by this prospectus:

• our Annual report on Form 10-K for year ended December 31, 2018, filed with the SEC on March 21, 2019;

• our Quarterly Report on Form 10-Q for the quarter ended March 31, 2019, filed with the SEC on May 9, 2019;

• our Current Reportson Form 8-K  filed on January 8, 2019, January 15, 2019 (amendment), February  1, 2019 (only the portion disclosed pursuant to Item 5.02), February  20, 2019,March 21, 2019, andMay 16, 2019;

• the description of our common stock contained in our registration statement on Form 8-A filed with the SEC on January 29, 2018 under Section 12 of the Exchange Act, including any amendment or report filed for the purpose of updating such description; and

• filings we make with the SEC pursuant to the Exchange Act after the date of the initial registration statement, of which this prospectus is a part, and prior to the effectiveness of the registration statement.

Nothing in this prospectus supplement shall be deemed to incorporate information furnished but not filed with the SEC pursuant to Item 2.02 or Item 7.01 of Form8-K.

Upon written or oral request, we will provide without charge to each person, including any beneficial owner, to whom this prospectus supplement is delivered, a copy of any or all of such information that has been incorporated herein by reference (other than exhibits to such documents unless such exhibits are specifically incorporated by reference into the documents that this prospectus supplement incorporates). Written or oral requests for copies should be directed to One Stop Systems, Inc., Attn: Chief Executive Officer, 2235 Enterprise Street #110, Escondido, California 92029, telephone number(877) 438-2724. See the section of this prospectus entitled “Where You Can Find More Information” for information concerning how to read and obtain copies of materials that we file with the SEC at the SEC’s public offices.

Any statement contained in this prospectus supplement, or in a document all or a portion of which is incorporated by reference, shall be modified or superseded for purposes of this prospectus supplement to the extent that a statement contained in this prospectus supplement, any future prospectus supplement or any document incorporated by reference modifies or supersedes such statement. Any such statement so modified or superseded shall not, except as so modified or superseded, constitute a part of this prospectus supplement.

S-13

PROSPECTUS

$100,000,000

Common Stock, Preferred Stock,

Debt Securities, Warrants, Subscription Rights and Units

From time to time, we may offer up to $100,000,000 aggregate dollar amount of shares of our common stock or preferred stock, debt securities, warrants to purchase our common stock, preferred stock or debt securities, subscription rights to purchase our common stock, preferred stock or debt securities and/or units consisting of some or all of these securities, in any combination, together or separately, in one or more offerings, in amounts, at prices and on the terms that we will determine at the time of the offering and which will be set forth in a prospectus supplement and any related free writing prospectus.

This prospectus describes the general manner in which those securities may be offered using this prospectus. Each time we offer securities, we will specify in an accompanying prospectus supplement and any related free writing prospectus the terms of securities offered and the offering thereof and may also add, update or change information contained in this prospectus.

The aggregate market value of our outstanding common stock held bynon-affiliates was approximately $22.7 million, which was calculated based on 9,762,341 shares of outstanding common stock held bynon-affiliates as of April 30, 2019, and a price per share of $2.33, the closing price of our common stock on April 30, 2019. Pursuant to General Instruction I.B.6 of FormS-3, in no event will we sell securities pursuant to this registration statement with a value more thanone-third of the aggregate market value of our common stock held bynon-affiliates in any12-month period, so long as the aggregate market value of our common stock held bynon-affiliates is less than $75.0 million. In the event that subsequent to the effective date of this registration statement, the aggregate market value of our outstanding common stock held bynon-affiliates equals or exceeds $75.0 million, then theone-third limitation on sales shall not apply to additional sales made pursuant to this registration statement. We have not sold any securities pursuant to General Instruction I.B.6 of FormS-3 during the 12 calendar months prior to, and including, the date of this registration statement.

You should read this prospectus, the information incorporated, or deemed to be incorporated, by reference in this prospectus, and any applicable prospectus supplement and related free writing prospectus carefully before you invest.

Our common stock is traded on the Nasdaq Capital Market under the symbol “OSS.” On April 30, 2019, the last reported sales price for our common stock on the Nasdaq Capital Market was $2.33 per share. None of the other securities we may offer are currently traded on any securities exchange. The applicable prospectus supplement and any related free writing prospectus will contain information, where applicable, as to any other listing on the Nasdaq Capital Market or any securities market or exchange of the securities covered by the prospectus supplement and any related free writing prospectus.

An investment in our securities involves a high degree of risk. You should carefully consider the information under the heading “Risk Factors” beginning on page 7 of this prospectus and any applicable prospectus supplement, before investing in our securities.

The securities described in this prospectus may be sold to or through underwriters or dealers, directly to purchasers or through agents designated from time to time. For additional information on the methods of sale, you should refer to the section entitled “Plan of Distribution” in this prospectus. If any underwriters, dealers or agents are involved in the sale of any securities with respect to which this prospectus is being delivered, the names of such underwriters or agents and any applicable fees, discounts or commissions, details regarding over-allotment options, if any, will be set forth in a prospectus supplement. The price to the public of such securities and the net proceeds we expect to receive from such sale will also be set forth in a prospectus supplement.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is May 15, 2019

TABLE OF CONTENTS

	PAGE
ABOUT THIS PROSPECTUS		1
PROSPECTUS SUMMARY		2
RISK FACTORS		7
FORWARD-LOOKING STATEMENTS		8
WHERE YOU CAN FIND MORE INFORMATION		9
INCORPORATION OF INFORMATION BY REFERENCE		10
USE OF PROCEEDS		11
PLAN OF DISTRIBUTION		12
DESCRIPTION OF CAPITAL STOCK		14
DESCRIPTION OF DEBT SECURITIES		19
DESCRIPTION OF WARRANTS		26
DESCRIPTION OF SUBSCRIPTION RIGHTS		28
DESCRIPTION OF UNITS		29
LEGAL MATTERS		29
EXPERTS		29

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement that we filed with the Securities and Exchange Commission, or SEC, using a “shelf” registration process. Under this shelf registration process, from time to time, we may sell any combination of the securities described in this prospectus in one or more offerings, up to an aggregate dollar amount of $100,000,000, subject to any applicable limits prescribed by General Instruction I.B.6 of FormS-3. Each time we sell securities under this shelf registration process, we will provide a prospectus supplement that will contain specific information about the terms of the offering. We have provided to you in this prospectus a general description of the securities we may offer.

We may also add, update or change in a prospectus supplement any of the information contained in this prospectus. To the extent there is a conflict between the information contained in this prospectus and any applicable prospectus supplement, you should rely on the information in such prospectus supplement; provided that, if any statement in one of these documents is inconsistent with a statement in another document having a later date—for example, a document incorporated by reference in this prospectus or any prospectus supplement—the statement in the document having the later date modifies or supersedes the earlier statement. You should read both this prospectus and any prospectus supplement together with additional information described under the next heading “Where You Can Find More Information.”

You should rely only on the information contained in or incorporated by reference into this prospectus or any applicable prospectus supplement. No dealer, salesperson or any other person is authorized to give any information or to make any representation other than the information and representations contained in or incorporated by reference into this prospectus or any applicable prospectus supplement. If different information is given or different representations are made, you may not rely on that information or those representations as having been authorized by us. You may not imply from the delivery of this prospectus and any applicable prospectus supplement, nor from a sale made under this prospectus and any applicable prospectus supplement, that our affairs are unchanged since the date of this prospectus and any applicable prospectus supplement or that the information contained in any document incorporated by reference is accurate as of any date other than the date of the document incorporated by reference, regardless of the time of delivery of this prospectus and any applicable prospectus supplement or any sale of a security. This prospectus and any applicable prospectus supplement may only be used where it is legal to sell the securities.

In this prospectus, unless the context otherwise requires, the terms “One Stop,” “OSS,” the “Company,” “we,” “us,” and “our” refer to One Stop Systems, Inc., a Delaware corporation.

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PROSPECTUS SUMMARY

This summary does not contain all the information that you should consider before investing in our securities. You should read the entire prospectus and the information incorporated by reference in this prospectus carefully, including “Risk Factors” and the financial data and related notes and other information incorporated by reference, before making an investment decision.

Our Company

One Stop Systems, Inc. (“OSS”) designs and manufactures high-speed computing systems for high performance computing (“HPC”) applications that require fast processing and storage of large information data sets. These applications include artificial intelligence (“AI”), machine learning, seismic exploration, security and defense. Drawing upon years of expertise in designing and manufacturing custom systems for original equipment manufacturers (“OEMs”), our systems are built using the latest graphical processing unit (“GPU”) and flash-based solid-state drive (“SSD”) storage technologies.

We first began designing and manufacturing custom systems for defense, manufacturing, and telecom customers in 1998 and have always strived to be a leading innovator in our space. When PCI Express (“PCIe”) – themain component-to-component interconnect used in all computers today – was introduced by Intel Corporation in 2005, OSS was the first manufacturer to design and producePCIe box-to-box interconnection products. Today, we believe we have grown to become one of the largest providers of PCIe adapters and expansion systems used worldwide. When GPU technology and flash-based SSD were first introduced to the market, we began designing systems that maximized the power of these technologies. We now produce computer systems with large numbers of GPU cards and SSDs that allow progressively faster processing capabilities. The more GPUs and flash storage available to a server, the faster it can process, store and retrieve data, resulting in time savings and lower cost in running applications. Military video imaging applications are a prime example of mission-critical use of this technology where the ability to quickly and accurately identify battlefield parameters is paramount. We leverage strong relationships with our market-leading customers and suppliers to position ourselves at the forefront of these industries.

We design, assemble and supply systems that attach to both existing servers through PCIe and systems that have servers included. These systems can be clustered together to create powerful “massive computing” engines that occupy less space and require less power and cooling than conventional systems. We also sell software used to operate large 100% SSD storage systems for defense systems and commercial applications.

OSS sells its products worldwide to industry leading companies like Cisco, disguise (formerly d3), National Instruments, Northrop Grumman, Oracle and Raytheon. We are a strategic partner to technology leaders that include NVIDIA, Intel, Western Digital, and Broadcom. We are investing in new market segments adjacent to our core product lines, including development of HPC storage management software and HPC cloud services. We anticipate continued growth in our target markets, and believe we can increase market share through technology leadership, engineering expertise, supply chain management and product innovation.

Industry Background

The worldwide HPC market is expected to grow from $35.6 billion in 2016 to $43.9 billion by 2021, representing a compound annual growth rate (“CAGR”) of 4.3%, according to Intersect 360 Research. We believe we are uniquely positioned as a leading provider of HPC servers, compute accelerators and flash storage arrays to thehigh-end of this growing marketplace.

HPC applications require significant computing capabilities to analyze large amounts of data quickly, and store and retrieve that data as necessary. Companies, financial institutions, governmental agencies and academic institutions are increasingly turning to HPC solutions to analyze vast amounts of data, and more quickly gain

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meaningful and actionable insights. Two key technologies, GPUs and SSDs, enable our systems to process and store data more efficiently than traditional systems. By harnessing significant quantities of these components, companies can process large volumes of data much more quickly and efficiently.

While traditionally used to drive display applications, today’s advanced GPUs have developed more powerful capabilitiesfor non-graphical data processing beyond that of typical CPUs (central processing units) that power computer motherboards. In fact, the capabilities and speedof GPU-accelerated computers are now driving significant advances in AI and machine learning. Vast amounts of data are being collected by internet searches, cameras, sensors and other data generating activities and GPUs can more quickly process sophisticated algorithms that can analyze this “Big Data” and reveal unique patterns that lead to new insights and knowledge.

AI and machine learning have begun to transform businesses worldwide, as these advances in computing speed and power come together to enable businesses to solve complex problems. Until recently, many of these algorithms would take weeks or months to produce results. In many cases, the necessary computing capabilities were so expensive, and required so much space and power, they were infeasible. This is where OSS comes in. By acceleratingthe state-of-the-art in terms of computing performance, high density (less space) and power efficiency, OSS enables HPC applications to produce results in minutes versus hours or days versus months. In this way, OSS is enabling new data-intensive applications and computational solutions that were previously considered impractical or impossible.

Our Core Strengths and Solutions

Over nearly 20 years, OSS has developed unique expertise and core competencies across the fundamental technologies of today’s rapidly expanding HPC marketplace. These valuable assets are embedded in our leading-edge engineering capabilities, the proprietary know-howcontained in our extensive library of designs, and brand equity from our reputation as a high quality producerof state-of-the-art custom and standard solutions across an array of markets. Our strengths lie in three core areas: high-speed system interconnect design, high-density system design, and storage management software.

High-Speed System Interconnect Design

Members of our technical team are experts in high-speed digital signaling design, particularly regarding PCIe and nvlink signaling. We specialize in the design and productionof state-of-the-art systems that incorporate the latest high-speed signaling techniques. Our expertise includes circuit design and circuit board layout and routing optimizations, with a focus on achieving the highest levels of signal integrity.

In our current systems, PCIe Gen 3 signals are propagated across multiple circuit boards, connectors and cables, with sufficient signal quality for the receiver to reliably recognize digital signal transitions occurring at 8 billion times per second. However, this is a continually advancing area of technology, and OSS has demonstrated the ability to keep up with the treadmill of technology over several generations of signaling speeds. In fact, we have consistently been among a handful of companies able to come to market first with the latest technology. We delivered the industry’s first PCIe-over-cable solutions for PCIe Gen 1, Gen 2 and Gen 3, and are currently on track to accomplish this again in Gen 4.

In HPC systems, the “need for speed” is constantly driving signaling speeds higher and higher. Our next generation of products that include PCIe Gen 4 and nvlink 2.0 will involve signaling of 16 billion and 20 billion transitions per second, respectively. A diminishing set of companies have the capabilities to design and produce robust, highly reliable systems at these speeds. We believe our core competency in large scale, high-speed design and layout will allow us to remain at the forefront of this growing and ever-evolving industry.

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High-Density System Design

In addition to signal integrity design expertise, we have amassed expertise and proprietaryknow-how in high-density HPC system design. This expertise allows us to develop extremely sophisticated systems that consume less space, weight and power than ever before possible. For multiple reasons, this high-density capability has played a role in our customer design wins.

For military applications, smaller size, weight and power (known as SWaP) is critical in many battlefield systems. One of our more significant recent design wins was for a military aircraft where our solid state storage solution replaceda hard-to-remove, 165-pound system with a seven-pound removable module. For solutions contained within data centers, density also plays a significant role. For an equivalent amount of compute power, the OSS solution provided a ten times (10x) reduction in both rack space and power consumption. Economically, this is very compelling, since the cost of data center space and electrical power over the life of the product often exceeds the cost of the computer hardware.

Storage Management Software

On May 9, 2017, OSS entered into an agreement to acquire the source code license for SSD array software known as “Ion” from Western Digital. In connection with the transaction, OSS acquired the software engineering teams that developed the software, with the intent that OSS provide ongoing support to existing Western Digital customers and new releases of the software. This new software team provides OSS with proven expertise that can support the development of SSD storage arrays with exceptional performance, density, reliability and mobility. We expect to leverage this capability with our existing products and services over time.

The Ion software provides an interface to a standard server so it can easily read and write data from an array of SSDs. Two key features set Ion apart from other storage system software products: its optimizationfor low-latency, which means an SSD array can return data to the requesting server much more rapidly than those relying upon other types of server software, and Ion’s support for removableand hot-swappable SSD modules that contain multiple SSDs. This feature is essential to applications that require removable and expandable data storage that spans multiple SSDs.

Having an established storage softwareand in-house software engineering allows OSS to easily produce semi-custom product variations as well as add new features and capabilities to its product portfolio. Future product features may include dataencryption, de-duplication and compression, as well as other capabilities requested by our customers.

Our Opportunity

OSS has positioned itself as a technology leader in several key emerging areas of HPC. These include GPU computing, SSD storage arrays and cloud services. These areas are growing rapidly, and each has enormous potential given how they are replacing older technologies in very large markets.

OSS has significant design libraries, expertise and a customer-first approach that enable us to win OEM design and manufacturing business. Since each OEM design win generates revenue streamsfor 3-5 years (and potentially longer for military systems), the business tends to layer new revenue growth with each win. OSS also has a track record of successful strategic mergers and acquisitions, and such future activity could further enhance our growth through the same layering concept.

We believe strong, profitable growth is key to providing increasing shareholder value. We see three key elements driving our growth and profitable outlook. First, many of our existing OEM and military program design-wins are in the early stages of production and we expect them to ramp up significantly. Second, our technology leadership and increasing market presence has supported an increasein design-win opportunities.

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Third, an enhanced acquisition capability (due to the additional funding and enhanced liquidity for our stock provided by the initial public offering) will enable us to complete more significant strategic acquisitions that enhance and complement our core strategic capabilities and current growth rate. We will continue to look for opportunities that can be accretive and enhance our overall position.

The Securities We May Offer

With this prospectus, we may offer common stock, preferred stock, debt securities, warrants, subscription rights to purchase our common stock, preferred stock or debt securities, and/or units consisting of some or all of these securities in any combination. The aggregate offering price of securities that we offer with this prospectus will not exceed $100,000,000, subject to any applicable limits prescribed by General Instruction I.B.6 of FormS-3. Each time we offer securities with this prospectus, we will provide offerees with a prospectus supplement that will contain the specific terms of the securities being offered. The following is a summary of the securities we may offer with this prospectus.

Common Stock

We may offer shares of our common stock, par value $0.0001 per share.

Preferred Stock

We may offer shares of our preferred stock, par value $0.0001 per share, in one or more series. Our board of directors or a committee designated by the board will determine the dividend, voting, conversion and other rights of the series of shares of preferred stock being offered. Each series of preferred stock will be more fully described in the particular prospectus supplement that will accompany this prospectus, including redemption provisions, rights in the event of our liquidation, dissolution or the winding up, voting rights and rights to convert into common stock.

Debt Securities

We may offer general obligations, which may be secured or unsecured, senior or subordinated and convertible into shares of our common stock or preferred stock. In this prospectus, we refer to the senior debt securities and the subordinated debt securities together as the “debt securities.” Our board of directors will determine the terms of each series of debt securities being offered.

We will issue the debt securities under an indenture between us and a trustee. In this document, we have summarized general features of the debt securities from the indenture.

Warrants

We may offer warrants for the purchase of debt securities, shares of preferred stock or shares of common stock. We may issue warrants independently or together with other securities. Our board of directors will determine the terms of the warrants.

Subscription Rights

We may offer subscription rights to purchase of common stock, preferred stock or debt securities. We may issue subscription rights independently or together with other securities. Our board of directors will determine the terms of the subscription rights.

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Units

We may offer units consisting of some or all of the securities described above, in any combination, including common stock, preferred stock, warrants and/or debt securities. The terms of these units will be set forth in a prospectus supplement. The description of the terms of these units in the related prospectus supplement will not be complete. You should refer to the applicable form of unit and unit agreement for complete information with respect to these units.

* * *

We were originally organized as One Stop Systems, LLC, a California limited liability company, in 1998 before converting into One Stop Systems, Inc., a California corporation in 1999. On July 6, 2016, we entered into a Merger Agreement and Plan of Reorganization with Mission Technology Group, Inc. (“Magma”) whereby Magma merged with and into OSS with OSS continuing as the surviving corporation. In connection with our initial public offering, we reincorporated as a Delaware corporation on December 14, 2017 and began trading as a public company on the Nasdaq Capital Market on February 1, 2018. On August 31, 2018, we acquired Concept Development Inc., a provider of specialty in-flight entertainment located in Irvine, California. On October 31, 2018, we acquired Bressner Technology GmbH located near Munich, Germany. Bressner is a valued-added reseller of high technology hardware.

Our principal executive offices are located at 2235 Enterprise Street, Suite 110, Escondido, CA 92029 and our telephone number is(760) 745-9883. Our website address is www.onestopsystems.com. Information contained in, or accessible through, our website is not part of this prospectus, and the inclusion of our website address is for reference purposes only.

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RISK FACTORS

An investment in our securities involves a high degree of risk. The prospectus supplement relating to a particular offering of securities will contain a discussion of the risks applicable to an investment in the securities offered. Prior to making a decision about investing in our securities, you should carefully consider the specific factors discussed under the heading “Risk Factors” in the applicable prospectus supplement, together with all of the other information contained or incorporated by reference in the prospectus supplement or appearing or incorporated by reference in this prospectus. You should also consider the risks, uncertainties and assumptions discussed under Part I, Item 1A, “Risk Factors,” in our Annual Report on Form 10-K for the fiscal year ended December 31, 2018, which is incorporated herein by reference, and may be amended, supplemented or superseded from time to time by other reports we file with the SEC in the future. The risks and uncertainties we have described are not the only ones we face. Additional risks and uncertainties not presently known to us or that we currently deem immaterial may also affect our operations.

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FORWARD-LOOKING STATEMENTS

This prospectus and documents incorporated herein by reference contain “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements involve a number of risks and uncertainties. We caution readers that any forward-looking statement is not a guarantee of future performance and that actual results could differ materially from those contained in the forward-looking statement. These statements are based on current expectations of future events. Such statements include, but are not limited to, statements about future financial and operating results, plans, objectives, expectations and intentions, costs and expenses, interest rates, outcome of contingencies, financial condition, results of operations, liquidity, cost savings, objectives of management, business strategies, debt financing, clinical trial timing and plans, the achievement of clinical and commercial milestones, the advancement of our technologies and our product candidates, and other statements that are not historical facts. You can find many of these statements by looking for words like “believes,” “expects,” “anticipates,” “estimates,” “may,” “might,” “should,” “will,” “could,” “plan,” “intend,” “project,” “seek” or similar expressions in this prospectus or in documents incorporated by reference into this prospectus. We intend that such forward-looking statements be subject to the safe harbors created thereby.

These forward-looking statements are based on the current beliefs and expectations of our management and are subject to significant risks and uncertainties. If underlying assumptions prove inaccurate or unknown risks or uncertainties materialize, actual results may differ materially from current expectations and projections. Factors that might cause such a difference include those discussed in Part I, Item 1A “Risk Factors” in our Annual Report on Form 10-K for the fiscal year ended December 31, 2018, as well as those discussed in this prospectus and in the documents incorporated by reference into this prospectus. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this prospectus or, in the case of documents referred to or incorporated by reference, the date of those documents.

All subsequent written or oral forward-looking statements attributable to us or any person acting on our behalf are expressly qualified in their entirety by the cautionary statements contained or referred to in this section. We do not undertake any obligation to release publicly any revisions to these forward-looking statements to reflect events or circumstances after the date of this prospectus or to reflect the occurrence of unanticipated events, except as may be required under applicable U.S. securities law. If we do update one or more forward-looking statements, no inference should be drawn that we will make additional updates with respect to those or other forward-looking statements.

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WHERE YOU CAN FIND MORE INFORMATION

We are subject to the informational requirements of the Securities Exchange Act of 1934, as amended, or the Exchange Act, and are required to file annual, quarterly and other reports, proxy statements and other information with the SEC. You may inspect and copy these reports, proxy statements and other information at the public reference facilities maintained by the SEC in Washington, D.C., 100 F Street N.E., Washington, D.C. 20549. Copies of such materials can be obtained from the SEC’s public reference section at prescribed rates. You may obtain information on the operation of the public reference rooms by calling the SEC at (800)SEC-0330. Additionally, the SEC maintains an Internet site (www.sec.gov) that contains reports, proxy and information statements, and various other information about us. You may also inspect the documents described herein at our headquarters, 2235 Enterprise Street #110, Escondido, California 92029, during normal business hours.

Information about us is also available at our website at www.onestopsystems.com. However, the information on our website is not a part of this prospectus and is not incorporated by reference into this prospectus.

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INCORPORATION OF INFORMATION BY REFERENCE

The SEC allows us to “incorporate by reference” information that we file with the SEC, which means that we can disclose important information to you by referring you to those other documents. The information incorporated by reference is an important part of this prospectus, and information we file later with the SEC will automatically update and supersede this information. We incorporate by reference the documents listed below and any future filings we make with the SEC under Section 13(a), 13(c), 14, or 15(d) of the Exchange Act prior to the termination of any offering of securities made by this prospectus:

• our Annual report onForm 10-K for year ended December 31, 2018, filed with the SEC on March 21, 2019;

• our Quarterly Report onForm 10-Q for the quarter ended March 31, 2019, filed with the SEC on May 9, 2019;

• our Current Reports onForm  8-K filed onJanuary 8, 2019,January  15, 2019 (amendment),February  1, 2019 (only the portion disclosed pursuant to Item 5.02),February  20, 2019, andMarch 21, 2019;

• the description of our common stock contained in our registration statement onForm 8-A filed with the SEC on January 29, 2018 under Section 12 of the Exchange Act, including any amendment or report filed for the purpose of updating such description; and

• filings we make with the SEC pursuant to the Exchange Act after the date of the initial registration statement, of which this prospectus is a part, and prior to the effectiveness of the registration statement.

Upon written or oral request, we will provide without charge to each person, including any beneficial owner, to whom this prospectus is delivered, a copy of any or all of such information that has been incorporated herein by reference (other than exhibits to such documents unless such exhibits are specifically incorporated by reference into the documents that this prospectus incorporates). Written or oral requests for copies should be directed to One Stop Systems, Inc., Attn: Chief Executive Officer, 2235 Enterprise Street #110, Escondido, California 92029, telephone number (877)438-2724. See the section of this prospectus entitled “Where You Can Find More Information” for information concerning how to read and obtain copies of materials that we file with the SEC at the SEC’s public offices.

Any statement contained in this prospectus, or in a document all or a portion of which is incorporated by reference, shall be modified or superseded for purposes of this prospectus to the extent that a statement contained in this prospectus, any prospectus supplement or any document incorporated by reference modifies or supersedes such statement. Any such statement so modified or superseded shall not, except as so modified or superseded, constitute a part of this prospectus.

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USE OF PROCEEDS

We will retain broad discretion over the use of the net proceeds to us from the sale of our securities under this prospectus. Unless otherwise provided in the applicable prospectus supplement, we intend to use the net proceeds from the sale of securities under this prospectus for general corporate purposes, which may include funding research and development, increasing our working capital and acquisitions or investments in businesses, products or technologies that are complementary to our own. We will set forth in the prospectus supplement our intended use for the net proceeds received from the sale of any securities. Pending the application of the net proceeds, we intend to invest the net proceeds in short-term or long-term, investment-grade, interest-bearing securities.

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PLAN OF DISTRIBUTION

We may sell the securities covered by this prospectus to one or more underwriters for public offering and sale by them, and may also sell the securities to investors directly or through agents. We will name any underwriter or agent involved in the offer and sale of securities in the applicable prospectus supplement. We have reserved the right to sell or exchange securities directly to investors on our own behalf in jurisdictions where we are authorized to do so. We may distribute the securities from time to time in one or more transactions:

• at a fixed price or prices, which may be changed;

• at market prices prevailing at the time of sale;

• at prices related to such prevailing market prices; or

• at negotiated prices.

We may directly solicit offers to purchase the securities being offered by this prospectus. We may also designate agents to solicit offers to purchase the securities from time to time. We will name in a prospectus supplement any agent involved in the offer or sale of our securities. Unless otherwise indicated in a prospectus supplement, an agent will be acting on a best efforts basis, and a dealer will purchase securities as a principal for resale at varying prices to be determined by the dealer.

If we utilize an underwriter in the sale of the securities being offered by this prospectus, we will execute an underwriting agreement with the underwriter at the time of sale and we will provide the name of any underwriter in the prospectus supplement that the underwriter will use to make resales of the securities to the public. In connection with the sale of the securities, we, or the purchasers of securities for whom the underwriter may act as agent, may compensate the underwriter in the form of underwriting discounts or commissions. The underwriter may sell the securities to or through dealers, and those dealers may receive compensation in the form of discounts, concessions or commissions from the underwriters or commissions from the purchasers for whom they may act as agent.

We will provide in the applicable prospectus supplement any compensation we pay to underwriters, dealers, or agents in connection with the offering of the securities, and any discounts, concessions or commissions allowed by underwriters to participating dealers. Underwriters, dealers and agents participating in the distribution of the securities may be deemed to be underwriters within the meaning of the Securities Act of 1933, or the Securities Act, and any discounts and commissions received by them and any profit realized by them on resale of the securities may be deemed to be underwriting discounts and commissions. We may enter into agreements to indemnify underwriters, dealers and agents against civil liabilities, including liabilities under the Securities Act, and to reimburse them for certain expenses. We may grant underwriters who participate in the distribution of our securities under this prospectus an option to purchase additional securities to cover any over-allotments in connection with the distribution.

The securities we offer under this prospectus may or may not be listed through the Nasdaq Capital Market any other securities exchange. To facilitate the offering of securities, certain persons participating in the offering may engage in transactions that stabilize, maintain or otherwise affect the price of the securities. This may include short sales of the securities, which involves the sale by persons participating in the offering of more securities than we sold to them. In these circumstances, these persons would cover such short positions by making purchases in the open market or by exercising their option to purchase additional securities. In addition, these persons may stabilize or maintain the price of the securities by bidding for or purchasing securities in the open market or by imposing penalty bids, whereby selling concessions allowed to dealers participating in the offering may be reclaimed if securities sold by them are repurchased in connection with stabilization transactions. The effect of these transactions may be to stabilize or maintain the market price of the securities at a level above that which might otherwise prevail in the open market. These transactions may be discontinued at any time.

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We may engage in at the market offerings into an existing trading market in accordance with Rule 415(a)(4) under the Securities Act. In addition, we may enter into derivative transactions with third parties, or sell securities not covered by this prospectus to third parties in privately negotiated transactions. If the applicable prospectus supplement indicates, in connection with those derivatives, the third parties may sell securities covered by this prospectus and the applicable prospectus supplement, including short sale transactions. If so, the third party may use securities pledged by us or borrowed from us or others to settle those sales or to close out any related open borrowings of stock, and they may use securities received from us in settlement of those derivatives to close out any related open borrowings of stock. The third party in these sale transactions will be an underwriter and will be identified in the applicable prospectus supplement. In addition, we may otherwise loan or pledge securities to a financial institution or other third party that in turn may sell the securities short using this prospectus. The financial institution or other third party may transfer its economic short position to investors in our securities or in connection with a concurrent offering of other securities.

We will file a prospectus supplement to describe the terms of any offering of our securities covered by this prospectus. The prospectus supplement will disclose:

• the terms of the offer;

• the names of any underwriters, including any managing underwriters, as well as any dealers or agents;

• the purchase price of the securities from us;

• the net proceeds to us from the sale of the securities;

• any delayed delivery arrangements;

• any underwriting discounts, commissions or other items constituting underwriters’ compensation, and any commissions paid to agents;

• in a subscription rights offering, whether we have engaged dealer-managers to facilitate the offering or subscription, including their name or names and compensation;

• any public offering price; and

• other facts material to the transaction.

We will bear all or substantially all of the costs, expenses and fees in connection with the registration of our securities under this prospectus. The underwriters, dealers and agents may engage in transactions with us, or perform services for us, in the ordinary course of business.

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DESCRIPTION OF CAPITAL STOCK

General

The following is a summary of the rights of our common stock and preferred stock, certain provisions of our certificate of incorporation and amended and restated bylaws, the investors’ rights agreement and of the General Corporation Law of the State of Delaware. For more detailed information, please see our certificate of incorporation, amended and restated bylaws and investors’ rights agreement, which are filed as exhibits to the registration statement of which this prospectus is a part, as well as the relevant provisions of the General Corporation Law of the State of Delaware. We reincorporated in the State of Delaware on December 14, 2017 prior to the closing of our initial public offering.

Our certificate of incorporation provide for one class of common stock. In addition, our certificate of incorporation authorizes shares of undesignated preferred stock, the rights, preferences and privileges of which may be designated from time to time by our board of directors.

Our authorized capital stock consists of 60,000,000 shares, all with a $0.0001 par value of per share, of which:

• 50,000,000 shares are designated as common stock; and

• 10,000,000 shares are designated as preferred stock.

As of April 30, 2019, there were 14,370,592 shares of our common stock outstanding and held of record by 92 stockholders.

Common Stock

Voting Rights

Each share of common stock entitles the holder to one vote with respect to each matter presented to our stockholders on which the holders of common stock are entitled to vote, including the election of directors. Holders of our common stock do not have cumulative voting rights. Except in respect of matters relating to the election and removal of directors on our board of directors and as otherwise provided in our certificate of incorporation or required by law, all matters to be voted on by our stockholders must be approved by a majority of the shares present in person or by proxy at the meeting and entitled to vote on the subject matter. In the case of election of directors, all matters to be voted on by our stockholders must be approved by a plurality of the votes entitled to be cast by all shares of common stock. Accordingly, the holders of a majority of the outstanding shares of common stock entitled to vote in any election of directors can elect all of the directors standing for election, if they so choose, other than any directors that holders of any preferred stock we may issue may be entitled to elect.

Dividends

Subject to preferences that may apply to any shares of preferred stock outstanding at the time, the holders of our common stock will be entitled to share equally, identically and ratably in any dividends that our board of directors may determine to issue from time to time.

Liquidation Rights

In the event of any voluntary or involuntary liquidation, dissolution or winding up of our affairs, holders of our common stock would be entitled to share ratably in our assets that are legally available for distribution to stockholders after payment of our debts and other liabilities. If we have any preferred stock outstanding at such time, holders of the preferred stock may be entitled to distribution and/or liquidation preferences. In either such case, we must pay the applicable distribution to the holders of our preferred stock before we may pay distributions to the holders of our common stock.

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Other Rights

Our stockholders have no preemptive, conversion or other rights to subscribe for additional shares, and there are no redemption or sinking funds provisions applicable to the common stock. All outstanding shares are, and all shares offered by this prospectus will be, when sold, validly issued, fully paid and nonassessable. The rights, preferences and privileges of the holders of our common stock will be subject to, and may be adversely affected by, the rights of the holders of shares of any series of our preferred stock that we may designate and issue in the future.

Preferred Stock

There are no shares of preferred stock outstanding. Under the terms of our certificate of incorporation, our board of directors has the authority, without further action by our stockholders, to issue up to 10,000,000 shares of preferred stock in one or more series, to establish from time to time the number of shares to be included in each such series, to fix the dividend, voting and other rights, preferences and privileges of the shares of each wholly unissued series and any qualifications, limitations or restrictions thereon, and to increase or decrease the number of shares of any such series, but not below the number of shares of such series then outstanding.

Our board of directors may authorize the issuance of preferred stock with voting or conversion rights that could adversely affect the voting power or other rights of the holders of the common stock. The issuance of preferred stock, while providing flexibility in connection with possible acquisitions and other corporate purposes, could, among other things, have the effect of delaying, deferring or preventing a change in our control and may adversely affect the market price of the common stock and the voting and other rights of the holders of common stock. We have no current plans to issue any shares of preferred stock.

Options

As of March 31, 2019, options to purchase 1,980,904 shares of our common stock were outstanding, of which 1,639,461 were vested and exercisable as of that date.

Restricted Stock Units

As of March 31, 2019, 308,750 Restricted Stock Units (RSUs) were outstanding, of which 0 were vested as of that date.

Warrants

As of March 31, 2019, 561,181 shares of common stock issuable upon the exercise of warrants were reserved for issuance. The warrants are currently exercisable andexpire six-seven years from the effective date of the issuance of said warrant. The warrants may not be sold, transferred, assigned, pledged or hypothecated during this offering.

Registration Rights

Demand Registration Rights

If, the holders of at least 50% of the registrable securities request in writing that we effect a registration with respect to their shares in an offering with an anticipated aggregate offering price, net of underwriting discounts and commissions, of greater than $10,000,000, we may be required to register their shares. We are obligated to effect at most two registrations for the holders of registrable securities in response to these demand registration rights, subject to certain exceptions.

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If we become entitled under the Securities Act to register our shares on a registration statement onForm S-3 and a holder of registrable securities requests in writing that we register their shares for public resale onForm S-3, the price to the public of the offering is $500,000 or more, we will be required to provide notice to all holders of registrable securities and to use our best efforts to effect such registration; provided, however, that we will not be required to effect such a registration if we have already effected two registrations on FormS-3 for the holders of registrable securities.

If the holders requesting registration intend to distribute their shares by means of an underwriting, the underwriter of such offering will have the right to limit the numbers of shares to be underwritten for reasons related to the marketing of the shares.

Piggyback Registration Rights

If at any time following the closing of this offering we propose to register any shares of our common stock under the Securities Act, subject to certain exceptions, the holders of registrable securities will be entitled to notice of the registration and to include their shares of registrable securities in the registration. If our proposed registration involves an underwriting, the managing underwriter of such offering will have the right to limit the number of shares to be underwritten for reasons related to the marketing of the shares.

In August 2018, we entered into a Common Shareholder Piggyback Registration Rights Agreement with a stockholder as part of an agreement in the purchase of Concept Development Inc.

Expenses

Ordinarily, other than underwriting discounts and commissions, we will be required to pay all reasonable expenses incurred by us related to any registration effected pursuant to the exercise of these registration rights. These expenses may include all registration, filing and qualification fees, printer and accounting fees relating or apportionable thereto, and the reasonable fees and disbursements of one counsel for the selling security holders.

Termination of Registration Rights

The registration rights terminate upon the earlier of two years after the closing of this offering, or for any particular holder with registration rights, at such time following this offering when such holder may sell its shares pursuant to Rule 144(b)(1) under the Securities Act.

Anti-Takeover Effects of Delaware Law and Our Certificate of Incorporation and Bylaws

Some provisions of Delaware law, our certificate of incorporation and our amended and restated bylaws contain provisions that could make the following transactions more difficult: an acquisition of us by means of a tender offer; an acquisition of us by means of a proxy contest or otherwise; or the removal of our incumbent officers and directors. It is possible that these provisions could make it more difficult to accomplish or could deter transactions that stockholders may otherwise consider to be in their best interest or in our best interests, including transactions which provide for payment of a premium over the market price for our shares.

These provisions, summarized below, are intended to discourage coercive takeover practices and inadequate takeover bids. These provisions are also designed to encourage persons seeking to acquire control of us to first negotiate with our board of directors. We believe that the benefits of the increased protection of our potential ability to negotiate with the proponent of an unfriendly or unsolicited proposal to acquire or restructure us outweigh the disadvantages of discouraging these proposals because negotiation of these proposals could result in an improvement of their terms.

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Undesignated Preferred Stock

The ability of our board of directors, without action by the stockholders, to issue up to 10,000,000 shares of undesignated preferred stock with voting or other rights or preferences as designated by our board of directors could impede the success of any attempt to change control of us. These and other provisions may have the effect of deferring hostile takeovers or delaying changes in control or management of our company.

Stockholder Meetings

Our amended and restated bylaws provide that a special meeting of stockholders may be called only by our chairman of the board of directors, chief executive officer or president, or by a resolution adopted by a majority of our board of directors.

Requirements for Advance Notification of Stockholder Nominations and Proposals

Our amended and restated bylaws establish advance notice procedures with respect to stockholder proposals to be brought before a stockholder meeting and the nomination of candidates for election as directors, other than nominations made by or at the direction of the board of directors or a committee of the board of directors.

Removal of Directors

Our certificate of incorporation provides that no member of our board of directors may be removed from office by our stockholders except for cause and, in addition to any other vote required by law, upon the approval of not less than two thirds of the total voting power of all of our outstanding voting stock then entitled to vote in the election of directors.

Stockholders Not Entitled to Cumulative Voting

Our certificate of incorporation does not permit stockholders to cumulate their votes in the election of directors. Accordingly, the holders of a majority of the outstanding shares of our common stock entitled to vote in any election of directors can elect all of the directors standing for election, if they choose, other than any directors that holders of our preferred stock may be entitled to elect.

Delaware Anti-Takeover Statute

We are subject to Section 203 of the Delaware General Corporation Law, which prohibits persons deemed to be “interested stockholders” from engaging in a “business combination” with a publicly held Delaware corporation for three years following the date these persons become interested stockholders unless the business combination is, or the transaction in which the person became an interested stockholder was, approved in a prescribed manner or another prescribed exception applies. Generally, an “interested stockholder” is a person who, together with affiliates and associates, owns, or within three years prior to the determination of interested stockholder status did own, 15% or more of a corporation’s voting stock. Generally, a “business combination” includes a merger, asset or stock sale, or other transaction resulting in a financial benefit to the interested stockholder. The existence of this provision may have an anti-takeover effect with respect to transactions not approved in advance by the board of directors.

Choice of Forum

Our certificate of incorporation provides that, unless we consent in writing to the selection of an alternative form, the Court of Chancery of the State of Delaware will be the sole and exclusive forum for: (1) any derivative action or proceeding brought on our behalf; (2) any action asserting a claim of breach of a fiduciary duty or other wrongdoing by any of our directors, officers, employees or agents to us or our stockholders; (3) any action

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asserting a claim against us arising pursuant to any provision of the General Corporation Law of the State of Delaware or our certificate of incorporation or bylaws; (4) any action to interpret, apply, enforce or determine the validity of our certificate of incorporation or bylaws; or (5) any action asserting a claim governed by the internal affairs doctrine. Our certificate of incorporation also provides that any person or entity purchasing or otherwise acquiring any interest in shares of our capital stock will be deemed to have notice of and to have consented to this choice of forum provision. It is possible that a court of law could rule that the choice of forum provision contained in our certificate of incorporation is inapplicable or unenforceable if it is challenged in a proceeding or otherwise.

Amendment of Charter Provisions

The amendment of any of the above provisions, except for the provision making it possible for our board of directors to issue preferred stock, would require approval by holders of at least two thirds of the total voting power of all of our outstanding voting stock.

The provisions of Delaware law, our certificate of incorporation and our amended and restated bylaws could have the effect of discouraging others from attempting hostile takeovers and, as a consequence, they may also inhibit temporary fluctuations in the market price of our common stock that often result from actual or rumored hostile takeover attempts. These provisions may also have the effect of preventing changes in the composition of our board of directors and management. It is possible that these provisions could make it more difficult to accomplish transactions that stockholders may otherwise deem to be in their best interests.

Transfer Agent and Registrar

The transfer agent and registrar for our common stock is Corporate Stock Transfer, Inc. The transfer agent and registrar’s address is 3200 Cherry Creek Drive South, Suite 430, Denver, CO 80209.

Exchange Listing

Our common stock is listed on The Nasdaq Capital Market under the symbol “OSS.”

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DESCRIPTION OF DEBT SECURITIES

General

We will issue the debt securities offered by this prospectus and any accompanying prospectus supplement under an indenture to be entered into between us and the trustee identified in the applicable prospectus supplement. The terms of the debt securities will include those stated in the indenture and those made part of the indenture by reference to the Trust Indenture Act of 1939, as in effect on the date of the indenture.

We may offer under this prospectus up to an aggregate principal amount of $100,000,000 in debt securities, or if debt securities are issued at a discount, or in a foreign currency, foreign currency units or composite currency, the principal amount as may be sold for an aggregate public offering price of up to $100,000,000. Unless otherwise specified in the applicable prospectus supplement, the debt securities will represent our direct, unsecured obligations and will rank equally with all of our other unsecured indebtedness.

We may issue the debt securities in one or more series with the same or various maturities, at par, at a premium, or at a discount. We will describe the particular terms of each series of debt securities in a prospectus supplement relating to that series, which we will file with the SEC. The prospectus supplement relating to the particular series of debt securities being offered will specify the particular amounts, prices and terms of those debt securities. These terms may include:

• the title of the series;

• the aggregate principal amount, and, if a series, the total amount authorized and the total amount outstanding;

• the issue price or prices, expressed as a percentage of the aggregate principal amount of the debt securities;

• any limit on the aggregate principal amount;

• the date or dates on which principal is payable;

• the interest rate or rates (which may be fixed or variable) or, if applicable, the method used to determine such rate or rates;

• the date or dates from which interest, if any, will be payable and any regular record date for the interest payable;

• the place or places where principal and, if applicable, premium and interest, is payable;

• the terms and conditions upon which we may, or the holders may require us to, redeem or repurchase the debt securities;

• the denominations in which such debt securities may be issuable, if other than denominations of $1,000 or any integral multiple of that number;

• whether the debt securities are to be issuable in the form of certificated securities (as described below) or global securities (as described below);

• the portion of principal amount that will be payable upon declaration of acceleration of the maturity date if other than the principal amount of the debt securities;

• the currency of denomination;

• the designation of the currency, currencies or currency units in which payment of principal and, if applicable, premium and interest, will be made;

• if payments of principal and, if applicable, premium or interest, on the debt securities are to be made in one or more currencies or currency units other than the currency of denomination, the manner in which the exchange rate with respect to such payments will be determined;

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• if amounts of principal and, if applicable, premium and interest may be determined by reference to an index based on a currency or currencies or by reference to a commodity, commodity index, stock exchange index or financial index, then the manner in which such amounts will be determined;

• the provisions, if any, relating to any collateral provided for such debt securities;

• any addition to or change in the covenants and/or the acceleration provisions described in this prospectus or in the indenture;

• any events of default, if not otherwise described below under “Events of Default”;

• the terms and conditions, if any, for conversion into or exchange for shares of our common stock or preferred stock;

• any depositaries, interest rate calculation agents, exchange rate calculation agents or other agents; and

• the terms and conditions, if any, upon which the debt securities shall be subordinated in right of payment to our other indebtedness.

We may issue discount debt securities that provide for an amount less than the stated principal amount to be due and payable upon acceleration of the maturity of such debt securities in accordance with the terms of the indenture. We may also issue debt securities in bearer form, with or without coupons. If we issue discount debt securities or debt securities in bearer form, we will describe material U.S. federal income tax considerations and other material special considerations which apply to these debt securities in the applicable prospectus supplement.

We may issue debt securities denominated in or payable in a foreign currency or currencies or a foreign currency unit or units. If we do, we will describe the restrictions, elections, and general tax considerations relating to the debt securities and the foreign currency or currencies or foreign currency unit or units in the applicable prospectus supplement.

Debt securities offered under this prospectus and any prospectus supplement will be subordinated in right of payment to certain of our outstanding senior indebtedness, including our credit facilities. In addition, we will seek the consent of the holders of any such senior indebtedness prior to issuing any debt securities under this prospectus to the extent required by the agreements evidencing such senior indebtedness.

Registrar and Paying Agent

The debt securities may be presented for registration of transfer or for exchange at the corporate trust office of the security registrar or at any other office or agency that we maintain for those purposes. In addition, the debt securities may be presented for payment of principal, interest and any premium at the office of the paying agent or at any office or agency that we maintain for those purposes.

Conversion or Exchange Rights

Debt securities may be convertible into or exchangeable for shares of our common stock. The terms and conditions of conversion or exchange will be stated in the applicable prospectus supplement. The terms will include, among others, the following:

• the conversion or exchange price;

• the conversion or exchange period;

• provisions regarding the convertibility or exchangeability of the debt securities, including who may convert or exchange;

• events requiring adjustment to the conversion or exchange price;

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• provisions affecting conversion or exchange in the event of our redemption of the debt securities; and

• any anti-dilution provisions, if applicable.

Registered Global Securities

If we decide to issue debt securities in the form of one or more global securities, then we will register the global securities in the name of the depositary for the global securities or the nominee of the depositary, and the global securities will be delivered by the trustee to the depositary for credit to the accounts of the holders of beneficial interests in the debt securities.

The prospectus supplement will describe the specific terms of the depositary arrangement for debt securities of a series that are issued in global form. None of us, the trustee, any payment agent or the security registrar will have any responsibility or liability for any aspect of the records relating to or payments made on account of beneficial ownership interests in a global debt security or for maintaining, supervising or reviewing any records relating to these beneficial ownership interests.

No Protection in the Event of Change of Control

The indenture does not have any covenants or other provisions providing for a put or increased interest or otherwise that would afford holders of our debt securities additional protection in the event of a recapitalization transaction, a change of control or a highly leveraged transaction. If we offer any covenants or provisions of this type with respect to any debt securities covered by this prospectus, we will describe them in the applicable prospectus supplement.

Covenants

Unless otherwise indicated in this prospectus or the applicable prospectus supplement, our debt securities will not have the benefit of any covenants that limit or restrict our business or operations, the pledging of our assets or the incurrence by us of indebtedness. We will describe in the applicable prospectus supplement any material covenants in respect of a series of debt securities.

Merger, Consolidation or Sale of Assets

The form of indenture provides that we will not consolidate with or merge into any other person or convey, transfer, sell or lease our properties and assets substantially as an entirety to any person, unless:

• the person formed by the consolidation or into or with which we are merged or the person to which our properties and assets are conveyed, transferred, sold or leased, is a corporation organized and existing under the laws of the U.S., any state or the District of Columbia or a corporation or comparable legal entity organized under the laws of a foreign jurisdiction and, if we are not the surviving person, the surviving person has expressly assumed all of our obligations, including the payment of the principal of and, premium, if any, and interest on the debt securities and the performance of the other covenants under the indenture; and

• immediately before and immediately after giving effect to the transaction, no event of default, and no event which, after notice or lapse of time or both, would become an event of default, has occurred and is continuing under the indenture.

Events of Default

Unless otherwise specified in the applicable prospectus supplement, the following events will be events of default under the indenture with respect to debt securities of any series:

• we fail to pay any principal or premium, if any, when it becomes due;

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• we fail to pay any interest within 30 days after it becomes due;

• we fail to observe or perform any other covenant in the debt securities or the indenture for 60 days after written notice specifying the failure from the trustee or the holders of not less than 25% in aggregate principal amount of the outstanding debt securities of that series; and

• certain events involving bankruptcy, insolvency or reorganization of us or any of our significant subsidiaries.

The trustee may withhold notice to the holders of the debt securities of any series of any default, except in payment of principal of or premium, if any, or interest on the debt securities of a series, if the trustee considers it to be in the best interest of the holders of the debt securities of that series to do so.

If an event of default (other than an event of default resulting from certain events of bankruptcy, insolvency or reorganization) occurs, and is continuing, then the trustee or the holders of not less than 25% in aggregate principal amount of the outstanding debt securities of any series may accelerate the maturity of the debt securities. If this happens, the entire principal amount, plus the premium, if any, of all the outstanding debt securities of the affected series plus accrued interest to the date of acceleration will be immediately due and payable. At any time after the acceleration, but before a judgment or decree based on such acceleration is obtained by the trustee, the holders of a majority in aggregate principal amount of outstanding debt securities of such series may rescind and annul such acceleration if:

• all events of default (other than nonpayment of accelerated principal, premium or interest) have been cured or waived;

• all lawful interest on overdue interest and overdue principal has been paid; and

• the rescission would not conflict with any judgment or decree.

In addition, if the acceleration occurs at any time when we have outstanding indebtedness that is senior to the debt securities, the payment of the principal amount of outstanding debt securities may be subordinated in right of payment to the prior payment of any amounts due under the senior indebtedness, in which case the holders of debt securities will be entitled to payment under the terms prescribed in the instruments evidencing the senior indebtedness and the indenture.

If an event of default resulting from certain events of bankruptcy, insolvency or reorganization occurs, the principal, premium and interest amount with respect to all of the debt securities of any series will be due and payable immediately without any declaration or other act on the part of the trustee or the holders of the debt securities of that series.

The holders of a majority in principal amount of the outstanding debt securities of a series will have the right to waive any existing default or compliance with any provision of the indenture or the debt securities of that series and to direct the time, method and place of conducting any proceeding for any remedy available to the trustee, subject to certain limitations specified in the indenture.

No holder of any debt security of a series will have any right to institute any proceeding with respect to the indenture or for any remedy under the indenture, unless:

• the holder gives to the trustee written notice of a continuing event of default;

• the holders of at least 25% in aggregate principal amount of the outstanding debt securities of the affected series make a written request and offer reasonable indemnity to the trustee to institute a proceeding as trustee;

• the trustee fails to institute a proceeding within 60 days after such request; and

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• the holders of a majority in aggregate principal amount of the outstanding debt securities of the affected series do not give the trustee a direction inconsistent with such request during such60-day period.

These limitations do not, however, apply to a suit instituted for payment on debt securities of any series on or after the due dates expressed in the debt securities.

We will periodically deliver certificates to the trustee regarding our compliance with our obligations under the indenture.

Modification and Waiver

From time to time, we and the trustee may, without the consent of holders of the debt securities of one or more series, amend the indenture or the debt securities of one or more series, or supplement the indenture, for certain specified purposes, including:

• to provide that the surviving entity following a change of control permitted under the indenture will assume all of our obligations under the indenture and debt securities;

• to provide for certificated debt securities in addition to uncertificated debt securities;

• to comply with any requirements of the SEC under the Trust Indenture Act of 1939;

• to provide for the issuance of and establish the form and terms and conditions of debt securities of any series as permitted by the indenture;

• to cure any ambiguity, defect or inconsistency, or make any other change that does not materially and adversely affect the rights of any holder; and

• to appoint a successor trustee under the indenture with respect to one or more series.

From time to time we and the trustee may, with the consent of holders of at least a majority in principal amount of an outstanding series of debt securities, amend or supplement the indenture or the debt securities series, or waive compliance in a particular instance by us with any provision of the indenture or the debt securities. We may not, however, without the consent of each holder affected by such action, modify or supplement the indenture or the debt securities or waive compliance with any provision of the indenture or the debt securities in order to:

• reduce the amount of debt securities whose holders must consent to an amendment, supplement, or waiver to the indenture or such debt security;

• reduce the rate of or change the time for payment of interest or reduce the amount of or postpone the date for payment of sinking fund or analogous obligations;

• reduce the principal of or change the stated maturity of the debt securities;

• make any debt security payable in money other than that stated in the debt security;

• change the amount or time of any payment required or reduce the premium payable upon any redemption, or change the time before which no such redemption may be made;

• waive a default in the payment of the principal of, premium, if any, or interest on the debt securities or a redemption payment;

• waive a redemption payment with respect to any debt securities or change any provision with respect to redemption of debt securities; or

• take any other action otherwise prohibited by the indenture to be taken without the consent of each holder affected by the action.

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Defeasance of Debt Securities and Certain Covenants in Certain Circumstances

The indenture permits us, at any time, to elect to discharge our obligations with respect to one or more series of debt securities by following certain procedures described in the indenture. These procedures will allow us either:

• to defease and be discharged from any and all of our obligations with respect to any debt securities except for the following obligations (which discharge is referred to as “legal defeasance”):

1. to register the transfer or exchange of such debt securities;

2. to replace temporary or mutilated, destroyed, lost or stolen debt securities;

3. to compensate and indemnify the trustee; or

4. to maintain an office or agency in respect of the debt securities and to hold monies for payment in trust; or

• to be released from our obligations with respect to the debt securities under certain covenants contained in the indenture, as well as any additional covenants which may be contained in the applicable supplemental indenture (which release is referred to as “covenant defeasance”).

In order to exercise either defeasance option, we must deposit with the trustee or other qualifying trustee, in trust for that

• purpose:

• money;

• U.S. Government Obligations (as described below) or Foreign Government Obligations (as described below) that through the scheduled payment of principal and interest in accordance with their terms will provide money; or

• a combination of money and/or U.S. Government Obligations and/or Foreign Government Obligations sufficient in the written opinion of a nationally-recognized firm of independent accountants to provide money;

that, in each case specified above, provides a sufficient amount to pay the principal of, premium, if any, and interest, if any, on the debt securities of the series, on the scheduled due dates or on a selected date of redemption in accordance with the terms of the indenture.

In addition, defeasance may be effected only if, among other things:

• in the case of either legal or covenant defeasance, we deliver to the trustee an opinion of counsel, as specified in the indenture, stating that as a result of the defeasance neither the trust nor the trustee will be required to register as an investment company under the Investment Company Act of 1940;

• in the case of legal defeasance, we deliver to the trustee an opinion of counsel stating that we have received from, or there has been published by, the Internal Revenue Service a ruling to the effect that, or there has been a change in any applicable federal income tax law with the effect that (and the opinion shall confirm that), the holders of outstanding debt securities will not recognize income, gain or loss for U.S. federal income tax purposes solely as a result of such legal defeasance and will be subject to U.S. federal income tax on the same amounts, in the same manner, including as a result of prepayment, and at the same times as would have been the case if legal defeasance had not occurred;

• in the case of covenant defeasance, we deliver to the trustee an opinion of counsel to the effect that the holders of the outstanding debt securities will not recognize income, gain or loss for U.S. federal income tax purposes as a result of covenant defeasance and will be subject to U.S. federal income tax

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on the same amounts, in the same manner and at the same times as would have been the case if covenant defeasance had not occurred; and

• certain other conditions described in the indenture are satisfied.

If we fail to comply with our remaining obligations under the indenture and applicable supplemental indenture after a covenant defeasance of the indenture and applicable supplemental indenture, and the debt securities are declared due and payable because of the occurrence of any undefeased event of default, the amount of money and/or U.S. Government Obligations and/or Foreign Government Obligations on deposit with the trustee could be insufficient to pay amounts due under the debt securities of the affected series at the time of acceleration. We will, however, remain liable in respect of these payments.

The term “U.S. Government Obligations” as used in the above discussion means securities that are direct obligations of ornon-callable obligations guaranteed by the United States of America for the payment of which obligation or guarantee the full faith and credit of the United States of America is pledged.

The term “Foreign Government Obligations” as used in the above discussion means, with respect to debt securities of any series that are denominated in a currency other than U.S. dollars, (1) direct obligations of the government that issued or caused to be issued such currency for the payment of which obligations its full faith and credit is pledged or (2) obligations of a person controlled or supervised by or acting as an agent or instrumentality of such government the timely payment of which is unconditionally guaranteed as a full faith and credit obligation by that government, which in either case under clauses (1) or (2), are not callable or redeemable at the option of the issuer.

Regarding the Trustee

We will identify the trustee with respect to any series of debt securities in the prospectus supplement relating to the applicable debt securities. You should note that if the trustee becomes a creditor of ours, the indenture and the Trust Indenture Act of 1939 limit the rights of the trustee to obtain payment of claims in certain cases, or to realize on certain property received in respect of any such claim, as security or otherwise. The trustee and its affiliates may engage in, and will be permitted to continue to engage in, other transactions with us and our affiliates. If, however, the trustee acquires any “conflicting interest” within the meaning of the Trust Indenture Act of 1939, it must eliminate such conflict or resign.

The holders of a majority in principal amount of the then outstanding debt securities of any series may direct the time, method and place of conducting any proceeding for exercising any remedy available to the trustee. If an event of default occurs and is continuing, the trustee, in the exercise of its rights and powers, must use the degree of care and skill of a prudent person in the conduct of his or her own affairs. Subject to that provision, the trustee will be under no obligation to exercise any of its rights or powers under the indenture at the request of any of the holders of the debt securities, unless they have offered to the trustee reasonable indemnity or security.

No Individual Liability of Incorporators, Stockholders, Officers or Directors

Each indenture provides that no incorporator and no past, present or future stockholder, officer or director of our company or any successor corporation in those capacities will have any individual liability for any of our obligations, covenants or agreements under the debt securities or such indenture.

Governing Law

The indentures and the debt securities will be governed by, and construed in accordance with, the laws of the State of Delaware.

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DESCRIPTION OF WARRANTS

General

We may issue warrants for the purchase of our debt securities, preferred stock, common stock, or any combination thereof. Warrants may be issued independently or together with our debt securities, preferred stock or common stock and may be attached to or separate from any offered securities. Each series of warrants will be issued under a separate warrant agreement to be entered into between us and a bank or trust company, as warrant agent. The warrant agent will act solely as our agent in connection with the warrants. The warrant agent will not have any obligation or relationship of agency or trust for or with any holders or beneficial owners of warrants. This summary of certain provisions of the warrants is not complete. For the terms of a particular series of warrants, you should refer to the prospectus supplement for that series of warrants and the warrant agreement for that particular series.

Debt Warrants

The prospectus supplement relating to a particular issue of warrants to purchase debt securities will describe the terms of the debt warrants, including the following:

• the title of the debt warrants;

• the offering price for the debt warrants, if any;

• the aggregate number of the debt warrants;

• the designation and terms of the debt securities, including any conversion rights, purchasable upon exercise of the debt warrants;

• if applicable, the date from and after which the debt warrants and any debt securities issued with them will be separately transferable;

• the principal amount of debt securities that may be purchased upon exercise of a debt warrant and the exercise price for the warrants, which may be payable in cash, securities or other property;

• the dates on which the right to exercise the debt warrants will commence and expire;

• if applicable, the minimum or maximum amount of the debt warrants that may be exercised at any one time;

• whether the debt warrants represented by the debt warrant certificates or debt securities that may be issued upon exercise of the debt warrants will be issued in registered or bearer form;

• information with respect to book-entry procedures, if any;

• the currency or currency units in which the offering price, if any, and the exercise price are payable;

• if applicable, a discussion of material U.S. federal income tax considerations;

• the antidilution provisions of the debt warrants, if any;

• the redemption or call provisions, if any, applicable to the debt warrants;

• any provisions with respect to the holder’s right to require us to repurchase the debt warrants upon a change in control or similar event; and

• any additional terms of the debt warrants, including procedures and limitations relating to the exchange, exercise, and settlement of the debt warrants.

Debt warrant certificates will be exchangeable for new debt warrant certificates of different denominations. Debt warrants may be exercised at the corporate trust office of the warrant agent or any other office indicated in

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the prospectus supplement. Prior to the exercise of their debt warrants, holders of debt warrants will not have any of the rights of holders of the debt securities purchasable upon exercise and will not be entitled to payment of principal or any premium, if any, or interest on the debt securities purchasable upon exercise.

Equity Warrants

The prospectus supplement relating to a particular series of warrants to purchase our common stock or preferred stock will describe the terms of the warrants, including the following:

• the title of the warrants;

• the offering price for the warrants, if any;

• the aggregate number of warrants;

• the designation and terms of the common stock or preferred stock that may be purchased upon exercise of the warrants;

• if applicable, the designation and terms of the securities with which the warrants are issued and the number of warrants issued with each security;

• if applicable, the date from and after which the warrants and any securities issued with the warrants will be separately transferable;

• the number of shares of common stock or preferred stock that may be purchased upon exercise of a warrant and the exercise price for the warrants;

• the dates on which the right to exercise the warrants shall commence and expire;

• if applicable, the minimum or maximum amount of the warrants that may be exercised at any one time;

• the currency or currency units in which the offering price, if any, and the exercise price are payable;

• if applicable, a discussion of material U.S. federal income tax considerations;

• the antidilution provisions of the warrants, if any;

• the redemption or call provisions, if any, applicable to the warrants;

• any provisions with respect to a holder’s right to require us to repurchase the warrants upon a change in control or similar event; and

• any additional terms of the warrants, including procedures and limitations relating to the exchange, exercise and settlement of the warrants.

Holders of equity warrants will not be entitled:

• to vote, consent, or receive dividends;

• receive notice as stockholders with respect to any meeting of stockholders for the election of our directors or any other matter; or

• exercise any rights as stockholders.

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DESCRIPTION OF SUBSCRIPTION RIGHTS

We may issue subscription rights to purchase our common stock, preferred stock or debt securities. These subscription rights may be offered independently or together with any other security offered hereby and may or may not be transferable by the stockholder receiving the subscription rights in such offering. In connection with any offering of subscription rights, we may enter into a standby arrangement with one or more underwriters or other purchasers pursuant to which the underwriters or other purchasers may be required to purchase any securities remaining unsubscribed for after such offering.

The prospectus supplement relating to any subscription rights we offer, if any, will, to the extent applicable, include specific terms relating to the offering, including some or all of the following:

• the price, if any, for the subscription rights;

• the exercise price payable for our common stock, preferred stock or debt securities upon the exercise of the subscription rights;

• the number of subscription rights to be issued to each stockholder;

• the number and terms of our common stock, preferred stock or debt securities which may be purchased per each subscription right;

• the extent to which the subscription rights are transferable;

• any other terms of the subscription rights, including the terms, procedures and limitations relating to the exchange and exercise of the subscription rights;

• the date on which the right to exercise the subscription rights shall commence, and the date on which the subscription rights shall expire;

• the extent to which the subscription rights may include an over-subscription privilege with respect to unsubscribed securities or an over-allotment privilege to the extent the securities are fully subscribed; and

• if applicable, the material terms of any standby underwriting or purchase arrangement which may be entered into by us in connection with the offering of subscription rights.

The description in the applicable prospectus supplement of any subscription rights we offer will not necessarily be complete and will be qualified in its entirety by reference to the applicable subscription rights certificate, which will be filed with the SEC if we offer subscription rights. We urge you to read the applicable subscription rights certificate and any applicable prospectus supplement in their entirety.

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DESCRIPTION OF UNITS

We may issue units consisting of some or all of the securities described above, in any combination, including common stock, preferred stock, warrants and/or debt securities. The terms of these units will be set forth in a prospectus supplement. The description of the terms of these units in the related prospectus supplement will not be complete. You should refer to the applicable form of unit and unit agreement for complete information with respect to these units.

LEGAL MATTERS

Procopio, Cory, Hargreaves & Savitch LLP, San Diego, California, will issue an opinion about certain legal matters with respect to the securities. Any underwriters or agents will be advised about legal matters relating to any offering by their own counsel.

EXPERTS

The consolidated financial statements of One Stop Systems, Inc. as of December 31, 2018 and 2017, and for each of the years then ended, incorporated by reference in this prospectus, have been so incorporated in reliance on the report of Haskell & White LLP, an independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

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$10,000,000

Common Stock

PROSPECTUS SUPPLEMENT

Noble Capital Markets

The date of this prospectus supplement is June 26, 2019