Sector 10, Inc. (SECI)

[Highland]

SCHEDULE 13G

CUSIP No.
81371J307
1.

Name of reporting person
I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (entities only)

KCG Americas LLC 26-4219373
2.

CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
(a) ¨ (b) ¨

3.

SEC Use only
4.

Citizenship or place of organization

Delaware
Number of shares beneficially owned by each reporting person with

5.

Sole voting power
22,466

6.

Shared voting power

Not applicable

7.

Sole dispositive power
22,466

8.

Shared dispositive power

Not applicable
9.

Aggregate amount beneficially owned by each reporting person
22,466
10.

Check box if the aggregate amount in Row (9) excludes certain shares* ¨

11.

Percent of class represented by amount in Row 9




7.35%
based on the outstanding shares reported on the issuer's 10-Q filed with the SEC for the period ending September 30, 2015.
12.

Type of reporting person*

BD